Rough Idle when Warm Renix

:doh: Im new to Renix jeeps I have a HO thats been very good to me .So anyway My 88 aw4 242 laredo runs great but after it warms up the Idle goes to chit 250 to 650 rpm . I know there is a bunch on sensors that go all wonky ,I have cleaned the TB and the tps Ive ran seafoam in the fuel and changed the fuel filter .This rig sat sense 07 has fresh tune up cap,rotor plugs wires .The rig was fine untill we went up to the snow level this weekend and I was driving in about 8 to 14 inches of snow depending on the ruts .Also this is a stock jeep Im wondering if it could be O2 sensor maybe please help need to fix for my wife to drive soon .

Very good possibility your oxygen sensor is the problem. Ever replace it? How exactly did you CLEAN your TPS? They don't take too well to that. If you wanna test/adjust your TPS, use the folowing instructions.

Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the 3.5 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

Ok thanks I think Im gonna swap my spare H.O. into it because it has Major blowbye and pukes smoke when in passing gear =( . Im sad but it what I get for buying a cheap Jeep and fixing it up oh well .I used carb cleaner and was careful to not mess it up and it worked fine afterward ,CPS I will look into and hope it gets better

I am pretty sure using Carb cleaner on a TPS (Throttle Position Sensor) would screw it up for good.

Disconnect the O2 sensor, and see if the problem goes away. IF the problem goes away, then the problem is either the O2 sensor, the wiring to the O2 sensor, or the power to the O2 sensor.

You need to do a lot of other swaps to change out the engine. ECU, sensors, are different, as is the flex plate, CPS, O2, TPS are all different!!

Have you tried running some engine cleaner products in the oil to free up stuck rings, checked to see if an injector is sticking open...??? What color is the blowby?

Pucking smoke only while in passing gear may not be the engine!!!! IT may be runing too rich at that point!

Ok I have not ran anything in the oil (like what) Ive used carb cleaner on tps's before and never had a bad results guess Ive been lucky because I cleaned it 2 weeks ago and it ran fine untill I went playing in the snow .what kind of treatment like a seafoam in the oil? or like some kind of stop ;eak ? Im not sure what you mean .

Try disconnecting the O2 sensor first. While doing that, check to see if the snow shoved the O2 sensor wires up against the exhaust and damaged the wires!!!

I would run some tests to determine what the problem is first. It might be carbon from too much fuel, caused by a bad sensor, bad grounds, bad O2 sensor, vacuum line leak near the MAP sensor vacuum line, or the MAP sensor vacuum line itself would make a lot of sense. Pull those spark plugs first, see what the look like, wet oil, brown, white, black, or burned or clean? It may not be an oil, engine parts issue, like stuck rings.

Then check for vacuum line leaks near the intake manifold, the MAP sensor on the firewall to the throttle body vacuum hose, brake vacuum hose. The post up the results. Also check the oil for water, and coolant for any oil just to cover those bases as well.

Get out an ohm volt multi meter and start running the sensor tests per the FSM. PM me if you don't have the FSM info.

And read the RenX files thread:

http://www.naxja.org/forum/showthread.php?t=905849&highlight=renx+files

IF, it needs some internal cleaning, try MMO, Marvel Mystery Oil, added to the oil.

Great thread thanks its going to be my Evening read also could use a suggestion for additive .I was thinking maybe Marvel Mystery in the combustion chambers? Also I am just going to buy a new O2 because this one looks poopy its discolored and looks OEM to me and my Dad also going to go over the intake / Exhaust bolts in the AM due to crap rain monsoon thats happening now ...Got to love the PNW =)

I prefer MMO added to the oil versus Seafoam. You can drain the oil, add 5 quarts of oil and 1 quart of MMO. Run it for 1,000 miles and change it. Use a good quality filter like Napa Gold or Wix. Do not use Fram oil filters on your Jeep.

I use wix ford filters because the hold a qt but thats on my 95 I dont think it will work on the renix upside down filter
MMO whats that ? MMO I get it now lol ok great thanks

You don't want to use a strong cleaner like Gumout on a dirty engine, as it break loose large hard carbon deposits, and clog the oil pump inlet, causing sudden death syndrome (SDS, LOL). MMO is a mild thin oil/cleaner....much safer, do it slowly.

Renix filters have a metric thread anyway, unlike the 91 and later motors which use the standard thread oil filters. Try the MMO and 1,000 mile oil change.

Also might I point out this thing sat for 5 years without being started .I will get some MMO and change the oil

Muddypunk,

For your blow-by problem here's a trick I've been doing since the 60s. I've pulled new engines from cars that had developed a blow-by problem and discovered the oil control rings were stuck closed by burnt oil. With the pistons on the bench, I sprayed them with Gumout and after a few seconds watched the rings snap open. Burnt oil can occur in the oil control rings if the oil return holes, in the pistons, are not large enough or there are not enough holes to allow proper drain back to the crankcase. The oil just sits there in the oil rings and cooks and eventually hardens. Now when I rebuild engines I alway increase the piston's oil return hole size to as large as the piston's oil groove width and /or increase the number of piston oil return holes. On a recent Mitsubishi V6 engine rebuild, five of six pistons had oil control rings frozen in place and the drain-back holes were corrected as described. This engine was not a high mileage engine.

Here's what I now routinely do for my tune-ups.
1. Pull spark plugs, which are to be replaced.
2. Spray one can of Gumout directly into all spark plug holes. This get the solvent right where it's needed; at the oil control rings.
3. Install new distributor cap, rotor, etc.
4. let engine set about an hour to allow Gumout to soak into the piston's oil control rings.
5. Install new spark plugs and fire engine.
6. When exhaust smoke clears up, shut down engine.
7. Drain oil, replace oil filter, refill crankcase with new oil.
8. Fire up again and let oil circulate and shutdown.

As I mentioned before, I've been doing this on all my engines since the 60s and I've never had a problem. Hope this helps.

Best regards,

CJR

Very interesting procedure. I like it. I can see how that would work very well!

I like it, too. Clarify please that you use one can of Gumout split evenly with the six spark plug holes, not one can per hole, right?

Cruiser,

I use one(1) can of Gumout sprayed in all cylinders, NOT one (1) can of Gumout sprayed in only one (1) cylinder.

Best regards,

CJR

cruiser54 said:

I like it, too. Clarify please that you use one can of Gumout split evenly with the six spark plug holes, not one can per hole, right?

Click to expand...

No doubt 6 full cans would work even better, right?

ROFLMAO!!!!:laugh3:

But might get a little costly at $9/can, LOL. On the other hand, if you had not asked, some idiot would have come along and used 6 cans on theirs!!!

Gotcha going, didn't I? I just wanted it clarified for others.

No doubt 6 full cans would work even better, right?
More than likely......

Cool Ill jump on it as soon as I get home off at the Inlaws for the Thanxgiving

**Carefully** pull off the rear smaller plastic tube that goes to the top rear of your valve cover and blow through it. Blow through the hole in the top of the valve cover and blow through the vacuum tap for it near the front of the intake manifold. If everything is clear, which iis highly unlikely, it may reduce your proble some. Also check and see if the air cleaner filter is oil soaked.

Carb cleaner or water on the TPS can cause all sorts of grief. I've had everything from stalling and very low idle, to a 2000 RPM idle caused by TPS issues.