No power & Idle speed wanders up & down

[Ecomike]

Current test results. With engine running for several minutes at idle, disconnecting the IAC motor connector has no effect, the Idle continues to cycle up and down the same as before.

I have replaced the following since I purchased it used 2 years ago. Oldest part I have replaced since acquiring it 2 years ago has maybe 8,000 miles on it max.

I replaced old worn out and suspect parts as follows: (Note that I installed a cooler thermostat early on, about 160 F, due to overheating problems which is still installed!) then all new parts in this order (roughly), *catalytic converter, *radiator, *fan clutch, *coolant overflow bottle, (*the CC was backing up exhaust, giving me an oil pressure over 80 PSIG, and it was overheating the engine, then the radiator was shot internally, fan clutch was bad....all causing the overheating) also replaced craked flywheel, starter, Speed or CPS sensor, fuel pressure regulator, Distributor, Cap, Rotor, plug wires, plugs, fuel injectors, TPS sensor, Ignition control module (ICM) and HV coil, ignition switch, Park / Neutral switch, head light switch, EGR valve, Idle speed adjust or idle air control or idle air stepper motor (pintle valve, has many names!!! same part), MAT sensor, O2 sensor, alternator, MAP sensor, .....high flow oil pump, new crank shaft bearings. All parts replacements made slight improvements in performance at the time they were replaced. Oil consumption is nearly zero.

This list does not include suspension parts, tires etc, steering gear box, that I have replaced, LOL. (after all it has 247,763 miles on it, it is Jeep Wagoneer Ltd. 4X4, almost fully restored)

Knock sensor not installed (damaged)! Wire not connected. I just discovered this part, what it does, where it goes,etc. It was not installed when I aquired the jeep.

I also just found the real coolant temp sensor (it was hiding...and the knock sensor thanks to help from a new friend with Renix manual who steered me to this list) and hooked it up 100 miles ago (tested it first, got 1000 ohms at about 120 F, slightly warm engine) to the correct but previously 1 of 2 mysterious open (unused) connectors on the wiring harness. It has not made any difference in operation!


Has excellent engine acceleration when the transmission is not in gear. Sounds and runs great. But when driving, transmission engaged in drive, the acceleration is like having 4 cyl, 60 hp engine in it. It takes 2 minutes to get up to 60 mph.

No vacuum leaks that I can find. Excellent fuel pressure, it is right on to spec, even flow tested it.

Today I disconnected the IAC motor connector and the TPS connector to the ECU, one at a time while it was idling and it made no difference, it continued to cycle between 900 rpm and 300 rpm (with out dying!!). When I pushed the accelerator it died when it tried to return to idle with the TPS sensor disconnected, but disconnecting the IAC had not effect after pushing the accelerator (with the Jeep parked). I found it quite interesting that I could disconnect the TPS and IAC motor connections while at idle and watch the idle speed continue to cycle from 300 rpm to 900 rpm and back to 300 rpm on a 20 second cycle with the jeep parked!!!!!

I have read the Renix manuals I just received (today & Wed), and everything else I could my hands on in the past and a good bit from this forum the last few days, and I think these results today are pertinent and new to the discussion of erratic idles on these Renix system XJ jeeps!

I have more test data (VOM readings on connectors, wiring harness, and grounds!!!!!) to post, which I will do ASAP. This is a good start to get the discussion going, I hope.

Lastly, the new O2 sensor was disconnected for about 3000 miles (wiring harness got fried on the exhaust manifold one day) and was only operated for about 100 miles before the harness connector was melted from its encounter with the exhaust manifold. So I never got a real good look at what the new O2 sensor did. Before the new O2 sensor, and after its abroupt disconnection, I always had unpredictable idle speed issues like most of those frequently reported here. The newest idle cycling symptom is brand new to me!!! It began after I fixed the wiring harness and reconnected the O2 sensor.

 

[Ecomike]

Here is more data. Tested point B on the TPS to ECU connector and read 13.3 ohms to ground. With engine running connector A read 2.92 V to ground all the time (at idle & WOT), and Connector C read .67 V at idle, .88 V at WOT to ground.

With TPS sensor connected to the TCU only I get A-C reading of 6.6K ohms to 4.2K ohms from idle to WOT. C to ground reads 6K ohms. B to ground reads 5.8K ohms.

Ground from engine valve cover to Bat. ground is 1.1 ohms.

TCU connector with connector disconnected from TPS reads 1670 ohms from pin D to ground, and 525 ohms from B (I think) to ground.

TPS sensor only at TCU connector read A-B .99K ohms to 1.10K ohms from Idle to WOT. B-D conn. and A-D conn. both read 4.0K ohms to 2.6K ohms from idle to WOT.

TPS sensor only at ECU connector A-B read 4.32K ohms at idle and WOT. B-C read 4.28 to 6.66K ohms from idel to WOT. A-C read 6.51K ohms to 4.23 ohms from idle to WOT.

All readings to ground on isolated TPS are infinite.

Tested D2 #8 connector pin "sensor ground" with ignition off and read 0.8 ohms, but read 8.8 ohms with ignition switch on.
Also it read .008 volts to batt ground from D2 #8pin with igniton switch on.
Read .021 to .032 volts from fast idle to slow idle on D2 pin 8 to batt ground.

D1 connector pin#3, ECU to ground read .017V to ground with ignition on, and .001 to .002V with engine running.

I used a set of jumper cables, #8 wire, to ground (test) the firewall to the engine and to the battery ground and it made no difference in the oscilating idle speed problem.

 

[langer1]

Lets stick to Voltage readings for now, B is ground and A is 5 volts "in" to the TPS so lets make sure you have that 5 volts in to the TPS. 4.75 should be fine.

All test will be from B with the TPS connected.

 

[Ecomike]

I pulled the ECU feed cable to the TPS and tested it with the engine running. A is reading a solid 5.00 Volts to ground and 5.00 volts to pin B. Pin B is grounded (reads 13.3 Ohms to Bat. ground, 0.0 volts to ground).

Now for the realy interesting find of the day. While getting your answer I discovered that I had the connectors reversed, so pin A was connected to pin C, and Pin B to Pin B. No idea how I missed this before, or how long or often it has been crossed over like this. I did not realise this connector could be reversed and still connect.

So I drove it a few miles and the performance has changed considerably. At first the system was immediately idling much faster, like 1200 rpm. I turned off the ignition and restarted it after 10 seconds off time, and the idle slowed back down to 700 rpm. Now it is cycling between 800 and 450 rpm at idle and 700 to 450 in drive while idling. Not as bad as before. It also has more power and acceleration now, but still has some power, acceleration, occasional stumble on acceleration and idle cycling issues, just not nearly as bad as before.

I suspect from my findings today that many others here have inadvertently hooked the ECU to TPS sensor connector up backwards like I did, as they have reported similar, seemingly unsolvable problems idle problems. So check your ECU to TPS connections!!!!!

In my case the A-B-C is visable on one connector while PED is visable on the other connector when attached properly. In other words the A-B-C marking is top side on one connector and bottom side on the other connector when A-A, B-B, and C-C are connected correctly. This seems wrong to me that they are not on the same side, meaning I think they should be both display side up when connected correctly, but perhaps the new sensor I installed last year has the connector on backwards from the factory??????
:wow:

I may need to check the wires on both sides more closely to be sure, but since the performance is so noticably improved, I suspect I now have the connectors and wires attached properly on the ECU to TPS connection.

 

[Ecomike]

OK Jeep fans, here is an update. I have put apx. 100 miles on it since my last post. Both Highway and stop and go city driving. Cold morning start up last 2 mornings outside temp was about 36 F, starts right up after 4 seconds of crank time. Runs like a champ at 800 rpm for about 50 seconds, then the idle slowly drops to 0 rpm, it dies. I restart, it repeats the cycle.

Third start it runs up to 1500 rpm for about two seconds, then drops to 800 rpm for 50 seconds, then slows to about 100 rpm, nearly dies but doesn't, then after 6 to 7 seconds at 100 rpm it runs back up to 800 rpm.

As it warms up to operating temp (currently tops out at about 140 F according to the gauge and the feel of the top radiator hose, note it still has 160 F thermostat in it that I plan to replace with a 192 F factory spec thermostat this weekend) the cycling continues but the range is only from about 450 RPM to 700 RPM once it is warmed up and it has stabilized.

After a few minutes at 60 mph, and then after stopping, it holds steady at 600 rpm in drive for about a minute, then it begins cycling again from 450 to 600 while in gear, and 450 to 700 rpm while in park.

In stop and go traffic it misses and stumbles when I give it the gas if it is in the slow rpm range of this mysterious cycle. When it is the high rpm range of the cycle it has plent of power, no stumbling, and great acceleration... mucho peep, when I press the gas peddle.

Has anyone ever heard of a bad O2 sensor causing this?????? It does this cycling at idle in the driveway even if I disconnect both the TPS and Idle air control steper motor at the same time!!!!! So I have eliminated them as a possible cause of this mysterious cycling (plus they are new).

Please :helpme:HELP!!!!!!! As Johnny-Five would say "Need Input"!!!!

 

[Blaine B.]

Did you disconnect the battery after changing around the plugs?

 

[Ecomike]

No, Not this time. I have tried that after replacing a sensor in the past but I saw no difference. Also, I was not sure if the Renix memory is volatile. Some chips have non-volatile memory and can only be cleared by writing over the old data. Is there a procedure for clearing the memory Renix? Does the ignition need to turned on with the battery disconected? If so how long do you leave it disconnected to clear the memory? What is the proper procedure?

 

[Blaine B.]

Not sure about the Renix...after you mention that some memory cannot be cleared without writing over it, I'm not sure.

 

[Ecomike]

I have 2 Renix manuals that I just recently acquired, unfortunately neither one discusses the memory reset issue.

 

[Ecomike]

This mornings first start was something new!:huh: I heard a loud vacuum leak in the interior cabin for about 2 minutes. During that time the idle speed was steady at 650 RPM and it had great power right from a cold start up (ambient about 50 F) until the vacuum leak completely disapeared. When the leak stopped the idle speed cycling resumed. So did the cycling pattern in the power / no power under acceleration cycle. Never found the leak as it never returned. Put about 60 miles on the old gal so far today. Too early to say for sure but todays miliage looks to up from about 9.0 to maybe 12 or 13 mpg.

Mike McGinness
South Houston, TX

 

[Ecomike]

Found one more problem. Turns out the O2 sensors 3 wire connection can also be easily connected backwards. :banghead:

Once I reversed the connection on the O2 sensor so that it is connected properly (A-A, B-B, C-C) the idle speed cycling abated!!! :sad1: Also the acceleration power is substantially restored, no more hesitation on acceleration.

It still acted up a few odd times over the first 2 days of the last 3 days, but I simply powered it down, waited 10 seconds for the idle stepper motor to reset, restarted her and she ran fine after that. Mpgs look to be up (from about 10 mpg) to about 13 to 14 mpg, with 3/4 highway, 1/4 city. Today I did not have any problems. I still need to install the 192 F thermostat to see if that restores the rest of the highway MPGs.

I also plan to replace the Temp sensor (as its electrical connectors have had better days) and the gauge temp sensor (already bought them) as they are the only remaining parts other than the ECU and the wiring harness left that I have not replaced.

I am really beginning to wonder how many others out there may have one of these two sensor's connectors hooked up backwards to the wiring harness. It is easy to do in a rush in the dark at night! It says a lot for the Renix system that it can survive and still start and run the jeep with two of them wired in backwards!!

Mike McGinness
South Houston, TX

 

[Ecomike]

Update:

Engine operating temperature has been a little higher the last few days. Possibly due to occasional leaner closed loop operation (?-finally?) but also due to higher ambient temps here. Still has a restored, reasonable amount of power, no hesitation or flat spots on TPS operation.

I changed the Cap and Rotor (they only had about 6,000 miles on them) 2 days ago but they had considerable oxidation and corrosion (scale) on them already!:gag: I had a small amount of idle miss, or shake at idle so I got suspicious and checked the rotor and cap. The small amount of shake or miss totally abated after installing the new rotor and cap. I will check the plugs and wires next.

I just filled up with gas (got 11.5 mpg on 50/50 highway/city driving, 147 miles, 12.78 gallons mostly used before replacing the rotor and cap) and I added Seafoam during the fill up with Chevron regular gas. Never used Seafoam before, but decided to try it after hearing RAVE reveiws of it here. My prior tank of gas was nearly 13 mpg, with 80% highway driving. I should mention that my city driving is mostly stop signs every two blocks on a 40 to 50 block round trip with the engine barely warmed up, but the highway miles (+20 mpg) still eludes me so I know it is not optimiozed yet!

I tested the 2 temp sensors (Gauge temp, ECU Temp sensor) using an ohm meter and although I did not have exact temp readings from another calibrated meter, or sensor to check there calibration, but they seem to working OK so I have delayed replacing them with new ones. They are not open or shorted in other words, and the ohm meter readings were right +/- say 15 degrees F.

I still plan to replave the 165 F thermostat real soon (next) as that seems like the most Usual Suspect now.

I forgot to mention earlier that I ran a vacuum gauge set of tests a few months ago and they indicated that all was well engine compression wise, head gasket, intake & exhaust manifold gasket and EGR valve wise. Last time I changed / inspected the spark plugs they looked great. So what ever my remaining gas mileage problem (s) are I do not think they are related to problems with engine vacuum, valves, piston rings, etc. Oil consumption is nearly zero. Oil pressure is good. Emissions are OK. Also, Fuel pressure was OK last time I checked it.

Like many others I am still looking for last ellusive fix to the low mileage problem.

Mike McGinness
South Houston, TX

 

[xjtrailrider]

Have you or the previous owner had the distributer out for any reason? I ask because my 90' had similar idle problems along with stumbles and miss-fires. It was off one tooth. I wouldnt hurt to check the indexing of the distributer just to eliminate that. I did the parts swap thing untill I went back to the basics, air, fuel, and spark!

 

[Ecomike]

Have you or the previous owner had the distributer out for any reason? I ask because my 90' had similar idle problems along with stumbles and miss-fires. It was off one tooth. I wouldnt hurt to check the indexing of the distributer just to eliminate that. I did the parts swap thing untill I went back to the basics, air, fuel, and spark!

Yes, and it was a learning experience unto itself. The first replacement distributor was a junk yard dog. Leaked oil internally, and then externally. That was fun. So I bought a rebuilt distributor from Autozone. Then I read and reread the repair manuals and deciphered the timing installation code and I finally got it installed properly (the prior one was not installed properly, and it was installed by a friend of mine who installed #2 the same way the prior, prior one (#1 of 3) was installed when I bought the jeep used, so it (#1) was in wrong too). Distributor#3 (a rebuilt from Autozone) I know is installed correctly and it is working right.

It was part of the problem until about 12 months ago.

This is one of those fun problems where several things are bad and all contributing to the same problem!

Late today, as recomended by others in other similar threads here, I removed and cleaned the connections on a ground wire between the firewall and the engine block on the driver sides and got the ohm meter reading between the aluminum valve cover and the battery ground, to drop from 13 ohms down to 0.2 ohms!!!! So I now know that the ground wire running from the battery to the engine block, which continues on to the firewall as one piece of wire, is well grounded at the firewall (to the negative battery terminal), but not to the engine block. The second ground wire I just cleaned and reinstalled runs from the firwall to the engine block only.

So, I restarted the Jeep and the engine idle jumped up to 1000 rpm! The idle had been stable for nearly 250 miles the past 4-5 days.

The idle refused to drop back down.

So, I turned off the jeep and waited 6 seconds for the IAC stepper motor (idle) to reset (see a Renix FSM manual on how the ECU resets the IAC every time the engine is powered down) then I restarted the jeep. This time it ran at 1200 rpm at idle. I rebooted it one more time (this Renix system acts like Microsoft windows, just restart, I mean reboot it, LOL) and low and behold the idle settled back down to normal and it runs fine now.

The next test will be to see if it made any permanent difference in the MPG's. It certainly made the Renix ECU adjust to the improved ground, evidenced by the sudden Idle speed changes and re-establishment of some kind of new baseline for the Renix Idle after 2 restarts and reset attempts by the ECU of the IAC (Idle Air Control) Motor.

Mike McGinness
South Houston, TX

 

[xjtrailrider]

I've been through the ground issues as well and ended up putting in a Optima red top and used the side negative terminal to add a extra chassis ground. It also helped my idle some. I went through and cleaned all of the connecters and put in new dielectric grease to help out the connections.

Glad you have your problem solved, now there is at lest 2 fully restored RENIX XJ's on the road!

Jon

 

[Ecomike]

Update: Tested gauge temperature with Infrared gauge today, and....

Question First: Does anyone know what the magic temperature is for the Renix to switch into the closed loop, high MPG mode? (1)

After fixing the weak ground issue I decided to check the voltage from B (ground) to C+ on TPS at idle with the power on (but engine off) today. It was about .65 V. The spec is .80 volts so I adjusted it. Got it to 0.800 V. I was surprised how sensitive and small the voltage change was as I moved the TPS. I locked it back in place reading 0.800 V.

Then I went to Harbour Tools and bought a small, key chain size portable, infrared temperature tester for $9.95, on sale. It has a range limit of -27 F to 230 F, but the price was right and it is real easy and super fast to use. Don't know how accurate it really is (claims +/- 2% or 2 C at an ambient of 23 C) but I was pretty impressed after using it. The readings were very repeatable.

Then I tested my exhisitng (old) Gauge Temperature Sender (GTS) and Coolant Temperature Sender with an ohm meter and they read, 280 ohms on the CTS and 252 ohms on the GTS. The FSM says that 160 F is 450 ohms, and 212 F is 185 ohms, and 100 F is 1,600 ohms.

Both sensors (the CTS and GTS) use the same variable resistance temperature device and have the same resitance at the same temperatures. Unfortunately, after plotting the temperatures from the FSM in MS Excel they do not appear to be linear, so it is not a typical thermistor, which as I recall is linear, so it might be a thermocouple(?), therefore I am not sure exactly what temperature 252 or 280 ohms is. If I had to guess I would say about 180 to 190 F. I have a 165 F thermostat currently in this jeep (as best as I recall, its been over 2 years now).

The gauge indicator was just barely below the second notch or line above the 100 F mark and just a bit more that 2 notches below the fourth mark which is labeled 212 F. Therefore, it seems clear that not only is the Thermocouple(?) non-linear but so is the gauge!

Has anyone ever mapped out the intermediate marked values on the water temperature guage between 100 and 212 F or from there to 260 F? My 1987 gauge has three notches between 100 and 212 F. I know now that they are not linear and that the first knotch is about 160 F, based on the infrared temperature readings I got today, and the second notch is about 190 F, at least with my current sensor, gauge and infrared meter combo.

Do these numbers and readings corelate with your alls readings?

Based on todays tests I now realise that my engine has been running at 160 to 190 F and not at 130 to 160 F as I previously thought.

I had previously thought that the last of my low MPG wowes might be due to the system running too cold (I thought it was running 130 to 160 F). Now I know (I think?) that it has been reaching at least 160 F in 3 to 4 minutes from the first morning start up, staying at a minimum of 160 F and has been running between 160 about 190 F the last few days, with an average of about 170 F, based on the infrared gauge)

So does anyone know what the magic temperature is for the Renix to switch into the closed loop, high MPG mode? (1)

So, although I have solved several problems (detailed in this thread) and improved the engine performance substantially since I bought this rig 2 years ago, I still think I am missing something big that is robbing of me of peak power and MPG's!!!!

May be time to finally pull the ECU and look at it and its wiring harness contacts.

Also, Could I have something wierd like worn lobes on the cam shaft that would not show up as anything other than power loss in higher gears and low MPGs? I suspect the engine may have had the heads and pistons redone before I purchased it.

I had to have the crankshaft main journal bearings replaced while upgrading to a high flow oil pump* last year, but the connecting rod journal bearings on the crankshaft were OK, indicating that perhaps this engine had been partially rebuilt at one time but that the mains were not replaced. The Jeep Odometer shows 244,454 miles. I did the oil pump and journal bearings when the oil pressure got down to about 13 PSI* one day and it scared me, before I read and realized that at idle 13 psi* is the minimum spec. This jeep has never burned or used oil since I bought it 2 years, and about 10,000 miles ago.

It seems to have plenty of get up and go power in first gear, and sounds and runs great in Park when you press the throttle it screams and roars. Idles smoothly from idle to 3300 rpm in park. Then has a slight vibration around 3,500 rpm and smooths out again at 4,000 rpm.

Anyway, I think the $9.95 for the infrared temp gauge was well worth it.

Runnig on empty!!!!!hasta

Mike McGinness
South Houston, TX

 

[Ecomike]

Update:

Idle speed problem(s) seem to be fixed now. Idle has worked flawlessly for the last week and 200 miles. See details in my prior posts about what all fixed it.

Power problem is partly solved as well. I have more power (like twice what it was when I bought it, but still half of what it should have, 50 to 100% WOT, is like 35% Throttle) but it is still way below what it should be.

Now for the good news. Two tanks of fuel ago I got 11.35 mpg 30% highway, 70% city. The current tank (1/4 tank left to go) is looking like I will hit 16 mpg with 80% highway and 20% stop and go neighborhood gas guzzling mode. So I must be getting about 18 mpg highway now (for the first time:sunshine.

The engine is running hotter, around 160 to 190F, even with a 165 F themostat and 65-75 F ambient temp.

I am tempted to say that the Renix has finally started kicking into the closed loop mode,:sunshine: running the engine leaner and therefore hotter inspite of a 165 F thermostat!!! I took the temperature readings in several places with my new infrared gauge.

This implies that the Renix will go into the closed loop mode at a temperature below the 195 F oem thermostat setting! It was running right at 160 to 165 F for over a year now with out the A/C on and with the 165 F thermostat. Therefore I am thinking that 165 F is high enough for the Renix to switch to the closed loop mode, if everything else is working correctly!

Since the cap and rotor had some wear on them (changed them again last week after less than 5,000 to 10,000 miles on them) I am going to take a fresh look at the plugs and wires next. I have double platinum champions and as I recall I changed them about 10,000 miles ago and the wires have about 5,000 miles on them.

 

[Ecomike]

Update and one correction:

I have Autolite single platinum AP3924 spark plugs (not dual platinum afterall ). Last MPG was 15.556 MPG, 75% highway, 25% stop and go traffic/city, so it is up quite a bit already.

I just installed a new set 7mm autozone lifetime warranty silcone wire set. I also pulled and checked the #3 &#4 spark plugs. The #3 plug still looked brand new, and the #4 plug had a small, minimal amount of carbon build up on it. Based on how it is running, and the looks of these two plugs and how good the old set loooked the last time I replaced them, I did not bother to check the rest.

 

[Ecomike]

Just filled up with gas. Got 13.3 MPG on 80% stopNgo city, 20% highway. So the mileage is definately improved since I started this thread. Still no real get and go power yet except in first gear and some in second gear. She runs pretty smoth at times and just a tiny bit rough at others making me suspect that the Seafoam cleaned out something and that something is still showing up and working its way through the injectors.

I have noted that I get some pinging now at WOT. Never had this problem (2 year history) before getting a new, working O2 sensor properly attached to the ECU harness and the old coolant sensor re-attached properly (see my prior mistakes in attaching them backwards, and the encounter with the exhaust manifold farther down this thread).

Once again I am now sure that the Renix is going into the closed loop mode, at least part time now evidenced by the large improvement in gas mileage. However, even with premium gas, and after running Seafoam two tanks ago, I am get some pinging at WOT. Also at WOT the engine RPM never gets over 2,500 rpm while in drive! The only sensor that is not installed and attached to the ECU is Knock sensor. But that would not affect the engine power, or lack of downshifting at WOT.

I picked up a new gas filter today. Will install in tomarrow or Saturday. My gas pump pressure and flow tested OK a while back but the pump has always run for about 7-8 seconds when I turn the ignition key on. Based on what I have read in the forum I am now suspecting the fuel filter (which I have never changed, so who knows how old or plugged up it is) and or the fuel pump.

Could a clogged fuel filter make the fuel pump run longer?

 

[Ecomike]

Jan. 6, 2007 update
I pulled and checked the #2 spark plug today (it looked like an oil leak at the plug). The spark plug looks great, almost new.

Lost 1.7 quarts of oil in last 300 miles. Added 1.7 quarts of 5w-50 Castrol Syntec, 100 % synthetic motor oil today. Decided to try out some synthetic for the first time. Now about 0.2 quarts past the full mark at 170 F on the dip stick. I did tighten the valve cover bolts a few weeks (days?) ago due to a valve cover gasket leak but I think I did it before I had the oil changed. The bolts were loose at that time. The Valve Cover gasket is less than 2000 miles old. I think the recent oil consumption (apx 1.5 quarts) happened after I tightened the valve cover gasket. Can not tell for sure but highest vertical leak area appears to be at the drivers side head gasket (?). Now wondering if the new valve cover gasket, or valve cover itself has a problem. Warped valve cover perhaps (?). It is alluminum with an unknown history. No oil in the PCV hose or air filter since I fixed the CCV hose to intake manifold line and the valve cover supply air line from the air filter about 6 weeks ago.

Rechecking that this week (just cleaned the entire area) around the the valve cover and head. It also may be leaking under the oil filter at the oil filter adapter to engine seal area (o-ring?).

I will clean that area tomarrow to help with future leak detection / isolation.

Note that some of the apparent oil consumption was from the 1/2 quart of Risolene and 1/2 quart of Marvel Mystery oil I used at the oil change about 550 miles ago. But the engine (lifters & valves) are running quiter since I used those additives.

I reached 80 miles on the trip meter using just under a 1/4 tank (gauge) of fuel according to the gas gauge. 80% highway mileage. Actually read 1/8th tank at 60 miles on the highway round trip before 20 miles of local stop and go trips. So gas mileage is still improved since I started working on these problems. WOT throtle is still at about 50% of what it should be, but there are no hesitation problems at all during acceleration, just a small bit of pinging when using Citgo fuels, gas.