Engine swap help

Hey guys,

I am new to your forum. I have a red 95 sport on 3” w/31’s 4.0HO 4spd Auto. Nothing fancy but it’s been good to me. I met a few of you guys at Holister 2 or 3 months back at one of your open events. There were a lot of cool rigs there.

So I am needing a bit of help. About 3 weeks ago no.1 rod let go. Punched out the side of the block, and sawed the pan in half. Ouch! So I found a 92 motor out of a limited that looked like it had been taken care of. I didn’t know the mileage so I did the bottom end. I polished and miced the crank. Installed new bearings, pump, timing chain, water pump. Did a cylinder pressure test on the stand, and everything seemed reasonably good.

I had swapped it out with the engine and had it installed about a week ago. I have spent the past week trying to get it to start. I have double checked everything many times. I have 135lbs on all cylinders except 2 cyl. No.2 is 145 and No.5 at 115. I have 38 lbs of fuel pressure, I have spark. My impression is that the spark timing is off. I have checked it while cranking w/ the timing light, and does not appear to be anywhere close to No. 1. I went through a number of old forums, related to flywheel variances, distributor indexing, timing chain alignment. I have tried 2 different crank pick ups, 2 different distributors. I have moved the distributor a tooth each direction, and tried starter fluid, all with no effect. I did a ruff indexing of the flywheel, to make sure it was the same as the one on the old motor. I have 3 sets of 4 square holes at 120 deg. like the original. Unless there is some subtle variance of this flywheel, I believe it is correct.

There is one symptom that would have meant something to me back in the day, but I do not know how it correlates to the computer control systems. When I crank it over, nothing noticeable happens, but sometimes when I release the key it will fire for a half dozen or a dozen cycles. This would have red flagged me to be looking at voltage at the coil on and off start circuit. But even this does not explain everything. I have spark. I am really baffled. It was running when I blew it up three weeks ago. I keep looking for something simple that I am missing, or forgot, but so far no luck! Any help would be appreciated.

Greg

Are you sure your not 180° on your dizzy? Had similar problem on my 87 renix i was sure timing was on, but I pulled the dizzy and dropped it in 180°, then she fired right up and ran like a champ.

I did swap the distributer 180 a couple days ago. No effect.

Greg

Are you sure that you have all of the injectors hooked up right, it is easy to cross up the wireing. I have the wireing color chart for the RENIX but not for the OBD1, maybe someone can post that info.

Hi,

check no 1 is tdc with the valves closed (TAPPETS ROCKING) piston at top take spark plug out , if ok look at rotor arm position should be adjacent no 1 on distributor cap, if it's out it will be down to your timing chain being out of wack..........good luck....

Did you use the flywheel off the 92 or 95 they are different and the crank senser could be reading the wrong signals.

Only In A Jeep XJ said:

Did you use the flywheel off the 92 or 95 they are different and the crank senser could be reading the wrong signals.

Click to expand...

Ditto...

I just installed a 4.0l from a '92 HO into my '87 Renix. Accidently used the flywheel from the HO, XJ wouldn't hold timing. The flywheels look very similiar at 11 o'clock at night!:confused1 It will run with the incorrect flywheel, very rough.

Thanks for the responces guys.



Are you sure that you have all of the injectors hooked up right, it is easy to cross up the wireing. I have the wireing color chart for the RENIX but not for the OBD1, maybe someone can post that info.

I will double check this although the the arnes was fairly stiff and the conectors seemed to fall into there respective positions. I think it would take some work to get them in the wrong positions.


check no 1 is tdc with the valves closed (TAPPETS ROCKING) piston at top take spark plug out , if ok look at rotor arm position should be adjacent no 1 on distributor cap, if it's out it will be down to your timing chain being out of wack..........good luck....

I have done this at least a halh dozen times.


Did you use the flywheel off the 92 or 95 they are different and the crank senser could be reading the wrong signals.

I did use the flexplate out of the 92. This was my strongest suspicion. I pulled the starter and rotated the engine and marked the the damper where the correlating openings in the flex plate. I counted the openings in the flywheel as I did this. I used the TDC mark to reference the posisions of the openings. It's hard to be completely accurate but it appeared to be very close to the 95. If they are different, it is very small. Are you sure there is a differance?

Greg

I just left the Stoneridgre Chrysler Jeep. The parts guy said that the FLex plate on 92 and 95 cherokee w/ the asian Trans have the same part numbers. I do not know what the differance is with the other trany, or the differance between RENIX and ODB 1. The two motors that I am working on appear to be Identicle. I am asuming that the cherokee I got the motor out of was also an HO/ODB 1. I am going to go look at the jeep the motor came out of again. I am close to pulling the motor out and starting from scratch. If anybody has any other ideas/knowledge I would appreciate the help.

92 and 95 are both OBD1, shouldn't be a problem there. Do you have the grounds hooked up? There should be a ground cable from negative battery to the engine at the dipstick tube holder bolt, and then a engine to chassis ground at the rear of the intake manifold/cylinder head area. It looks like a braided strap.

Just a hunch.

92 and 95 are both OBD1, shouldn't be a problem there. Do you have the grounds hooked up? There should be a ground cable from negative battery to the engine at the dipstick tube holder bolt, and then a engine to chassis ground at the rear of the intake manifold/cylinder head area. It looks like a braided strap.

Yes, I have all the grounds conected.Your thinking that a week ground is causing the computer to respond incorrectly? It would be easy enough to recheck these conections, or even add one or two more between the block and chassi to eliminate this posability?

I do have spark, it does not show up at TDC. Is it accurate to expect to see the timing mark near TDC during cranking? On other ODB 1's I have worked on it was nessasary to cross pins on a deticated conector to disable the computer to check and adjust the timing. Is there a way to do this on the jeep? It could help narrow down the nature of the problem.

Just to clarify, the inputs that the computer uses to determins spark timing is based on inputs from Crank & cam sensors, and the only mechanical influences on these would be timeing chain and distributer shaft orientation. I am assuming that because starting fluid did not influence the sympoms that the issue was ignition related and the sensors on the and around the manifold influencing fuel mixture would not be influencing ignition significantly.

I appreciate the help.

Greg

The flywheels/flexplates are different between RENIX and HO, but all the OBD-I should be the same, and all the OBD-II years should be the same (and the OBD-I and OBD-II may be the same.) The difference is that the RENIX CPS works on a different principle than the HO (the HO is a Hall Effect sensor - I'm not sure how the RENIX works.)

You might want to check my XJOG (groups.yahoo.com/group/XJOG) - I know I've got wiring diagrams up there, and they may apply to your 1992. Since Yahoo! just increase group fileshare space, I'll probably be adding more (once I can finally get a damn scanner...) However, it is easy to "swap a pair" on the injection harness, which will throw things out of kilter.

It is possible for a "weak" ground (dirty or corroded connections would cause a "floating ground") but you should still be able to run with them - just not well. When you disassemble your grounds to check them, clean the chassis down to BARE METAL over an area about the size of a postage stamp, and apply corrosion inhibitor on reassembly. Use your wire brush on the ring lugs as well (bare, shiny metal,) and reterminate wiring if you think it's necessary. You've got a 1992, so you've got three "main ground" connections - from the battery to the fenderwell, from the battery to the engine, and from the engine to the firewall. There are some "ancillary ground" connections to the chassis as well - give them the same treatment (clean, protect, and reterminate if necessary.) There are also several grounds for sensors at the main engine ground to the battery - check those as well. I'm not sure where the other ones are, offhand.

With the HO system, the main timing signal is generated by the crankshaft position sensor, with a synchronisation input from the camshaft sensor. I know that RENIX will run without the camshaft sensor, but I don't know about HO (RENIX is more flexible about running conditions than HO - I can turn the distributor 180* with the engine running, and the damn thing won't even stumble...) However, do check both sensors - I don't have a 1992FSM, but I've got a 1991, and the procedures should be similar.

I think your on to something. I pulled the battery leads/cables. I don't have much concern for the grounds on the engine or firewall, but I remember when I changed the oil before the engine went south that the battery terminals were badly caroded. After the engine went the first thing I did before tearing into it was degrese the engine compartment. Well it took all the carossion off the terminals, and I forgot about it. I have the charger on the battery tonight and I will repair/replace the terminals in the morning. I hope it is that simple.

Greg

Well I built new battery cables out of #4 welding cable. Soldered copper lugs with heat shrink bolted to new terminals with anti Ox on all conections. Soldered and heat srunk lug on the lead to fuse panel. new bradded ground strap to the fender wall. Heavy duty! No more corossion on this baby!

Won't start! Crap!

At this point the Valve cover is just set in place along with the timing cover. The damper is off. I set the radiator in so I could plug the trans. lines in so I could crank it over. I pulled the injection solinoid so it won't start and put the damper on as far as I can by hand. Not far enough to start the bolt. I wanted to be able to see the timing mark. I cranked it over with the timing light. I found the mark at about 3 O'clock. That is at least 45 deg. retarted. My nephew was over so we through his computer from his 93 5spd in. Timing was the same. I pulled the nut on the distributer and moved it around will we cranked it. The timing changed with it. So I pulled the distiributer out again (for about the tenth time) I rotated the rotor clockwise one tooth. Checked the timing, it's firing at TDC. ?????? I'm baffeled. I pull no.1 and set it up on TDC. The rotor is now half way betwen #1 and what would it be #5? Well past #1! at 90 deg.to the block. This dosn't make any sence to me, but OK, lets try it. Pull the damper, plug in the injection solinoid and it starts first click! It's missing on one cyl. but it runs! Wa Hoo! Put my computer back in, and it runs! Wa Hoo! I am still baffeled why it is runing with the rotor in that orientation, but who am I to argue. I had tryed the distributer in this orientation at least two different times last week, so maybe it was a combination of rotor position and the grounding? Last week the timing mark was showing up in differnt places. Who knows? I will put it back together and sort the rest of it out tomarrow.

Thanks to everyone for the help!

Greg

Stupid question - are you sure you're looking at distributor rotation in the right direction?

Firing order is 1-5-3-6-2-4, #1 on the distributor should be 180* away from the engine block (directly opposite, across the distributor) and the distributor turns clockwise.

Dumb question - I just want to make sure you're not "misreading" something by getting it reversed out of sheer frustration. I've been there, and so have many others...

Lord Humungus said:

Just walk away, and I will spare your lives. Just walk away...

Click to expand...

Yep, I have checked it many times, and I have had others check it as well. The rotor is at 180, pointing directly away from the engine, at 6 oclock. What is baffeling is that #1 is at about 5 or 5:30. The surface of the rotor appears to be completly past the elctrode for #1 at this point. Oh well! It sounds like it is in the right place.

As far as the miss, it is one hole. It could be a plug or a wire. I did a cylinder presure test when it was on the stand, so I don't think it is a dead hole.

Again, I appriciate the help.

Greg