TBI 5.7 swap in my YJ

Hello everyone. I have been reading here a fair amount and decided it was finally time to join. I will be getting a cable and Tunerpro Rt soon so I can dive into this stuff that I know nothing about. It should be an adventure for sure.

Current state of things... My Jeep runs, but not like it should. It is fine when cold, but falls on it's face once warmed up.

Immediate known issues, TPS readings with volt meter are .12 volts up to a little over 2 volts at WOT. Will be replacing TPS tonight. Also, I am only running a single wire o2 sensor on the manifold.

https://drive.google.com/uc?id=1jxG_...5cUlfhci-1ZI7L

Hmmm, did you get your Jeep that muddy with the TBI system?

dave w

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Originally Posted by dave w

Hmmm, did you get your Jeep that muddy with the TBI system?

dave w

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I did. It was just the one little mud puddle. The Jeep was already stumbling before then so that was the only obstacle encountered before heading back home.

You finally joined! Awesome!

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Originally Posted by c5wagner

You finally joined! Awesome!

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Yeah.... I suppose it is time to start learning something new. I appreciate your help thus far. Hopefully tonight the new TPS gets me running well enough to get on the trails this weekend. I have to work tomorrow and Friday nights and be 3 hours from home by 8:30 Saturday morning to work on trails. Tonight is all I have.

I put in a new TPS and a new MAP last night. It fired up and idled fine as it usually does. I backed it out of the shop to warm up and it shuts off and won't start. I have fuel, but no spark. C'mon... I just want this thing to work. I won't be able to get back to it for a couple days now. I was really trying to have it running good by Saturday because we will be pre-running the trails for the Bantam Jeep Heritage Festival. Oh well.

How big of a deal is the 3 wire 02 sensor? This is a trail Jeep. Fuel economy is not a concern. There is wiring left for it so I assume the ECM is looking for it.

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Originally Posted by DaddyJeep

How big of a deal is the 3 wire 02 sensor? This is a trail Jeep. Fuel economy is not a concern. There is wiring left for it so I assume the ECM is looking for it.

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Easy, just make sure you have a switched 12v output and good ground for the heater.

https://www.amazon.com/s?k=AFS74&ref=nb_sb_noss

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Originally Posted by PlayingWithTBI

Easy, just make sure you have a switched 12v output and good ground for the heater.

https://www.amazon.com/s?k=AFS74&ref=nb_sb_noss

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The wiring is intact. I just need to plug it in. The biggest part would be welding a bung in the exhaust, which really isn't a big deal either. The question though was is it that necessary to have?

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Originally Posted by DaddyJeep

The wiring is intact. I just need to plug it in. The biggest part would be welding a bung in the exhaust, which really isn't a big deal either. The question though was is it that necessary to have?

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Well, with the heated O2 my truck goes into C/L shortly after I pull out of my driveway and, after some tuning with Dave W's help, BLM stays ~128. If you're gonna do a lot of low speed idling/driving and your bung is farther from your heads you may not get good feedback from it being too cold.

Perhaps the ignition module inside the distributor is faulty, causing the no start? If you replace the ignition module, use "Heat Sink" grease. Heat Sink grease is basically die-electric grease with aluminum oxide added to provide SUPERIOR heat transfer. Heat Sink grease is more commonly used for EXPENSIVE Audio Amplifiers. GM uses EXPENSIVE Heat Sink grease under the ignition module, aftermarket ignition module suppliers use the lower cost die-electric grease or simply don't supply any heat transfer grease at all with the ignition module. HEAT will KILL an ignition module. Ever wonder why the L31 Vortec 350 has an externally mounted ignition module?

dave w

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Originally Posted by dave w

Perhaps the ignition module inside the distributor is faulty, causing the no start? If you replace the ignition module, use "Heat Sink" grease. Heat Sink grease is basically die-electric grease with aluminum oxide added to provide SUPERIOR heat transfer. Heat Sink grease is more commonly used for EXPENSIVE Audio Amplifiers. GM uses EXPENSIVE Heat Sink grease under the ignition module, aftermarket ignition module suppliers use the lower cost die-electric grease or simply don't supply any heat transfer grease at all with the ignition module. HEAT will KILL an ignition module. Ever wonder why the L31 Vortec 350 has an externally mounted ignition module?

dave w

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That is the first place I will be looking Dave. It is a new module, was last year anyway, but it seems like a likely culprit. I will be sure to get some better heat sink grease either way.

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How big of a deal is the 3 wire 02 sensor?

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It helps some with corrections for altitude, weather, and temperature. With a working O2 sensor the tuning can be off a little and the engine can still run fairly well.

.... Still broken.


I tried a couple spare ICMs that I had last night. No change. I really have no idea if the spare ICMs were any good or not, but it was worth a shot. I am going to see if I can get them tested today.

I did order an AC Delco 3 wire o2 sensor last night and a cable so I can start diving in to this tuning stuff... at least diagnostic stuff anyway.

No one local can test the ICM, but Advance had one in stock so I swapped my lifetime warranty one for another.

Did you wire in the diagnostics port and a check engine light? Maybe that would give you a better idea of a bad sensor or some other issue.

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Originally Posted by c5wagner

Did you wire in the diagnostics port and a check engine light? Maybe that would give you a better idea of a bad sensor or some other issue.

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I read that the 7427 doesn't flash codes like older computers so I have not bothered yet. My cable is ordered so I will be getting to that soon. I do try to avoid throwing parts at it without verifying that I have identified a problem. Since I got a free replacement for the ICM it made sense.

The 7427 does flash codes like the older ecms, I had a 95 k1500 while I was in high school that absolutely flashed codes when jumped.

So, I picked up a new pick up coil and got that installed inside the distributor even though the original tested fine. No change. The only thing that I haven't replaced with new is the Ignition Coil. I have a couple and they test fine so I didn't see the need to spend more money.

Here is what I found though.... While cranking I am not getting spark or injector pulse. As the cranking stops I get a small burst of both spark and injector pulse. I am thinking I may be losing power during cranking. I am just not sure where to look do diagnose that... Thoughts? I worked on it a little Friday, but I just needed a break from it I guess so I did yard work the rest of the weekend.

Maybe try a known good computer (16197427)?

dave w

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Originally Posted by dave w

Maybe try a known good computer (16197427)?

dave w

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Yeah.... I have tried the original computer that I was running that was from a 5.0 truck and the one that I have from a 5.7 truck. Both computers would make it run last week.

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Originally Posted by DaddyJeep

So, I picked up a new pick up coil and got that installed inside the distributor even though the original tested fine. No change. The only thing that I haven't replaced with new is the Ignition Coil. I have a couple and they test fine so I didn't see the need to spend more money.

Here is what I found though.... While cranking I am not getting spark or injector pulse. As the cranking stops I get a small burst of both spark and injector pulse. I am thinking I may be losing power during cranking. I am just not sure where to look do diagnose that... Thoughts? I worked on it a little Friday, but I just needed a break from it I guess so I did yard work the rest of the weekend.

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Is your ignition switch wired correctly? You should have power on when in both key on and start positions.

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Originally Posted by PlayingWithTBI

Is your ignition switch wired correctly? You should have power on when in both key on and start positions.

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I would have to say it is. It used to work. I have had it running for a couple years since I originally swapped in this engine.

I did some diagnostics today and am really getting no where as usual. I guess I am not really getting no where. I am at least verifying that things are not my problem. My PCM appears fine and keeps voltage in run and crank as it should. My coil is getting voltage in run and crank as it should. I did finally wire in my ALDL plug and check engine light. I pulled codes 43, 59, 67, 82. Nothing there screams that I have a problem. I know 43 is knock sensor related, but the rest are tranny or A/C, which I don't have either so no surprise.

This past week I had a problem like you described. Running fine when cold but falling on it's face when warm. I ended up having 3 bad spark plug wires that rubbed through on the transmission dipstick bracket that worked fine until engine was warm for some reason....... Maybe double check your spark plug wires?

I will keep that in mind c5wagner. I am really leaning towards CTS though, but we will see. I need to get a cable though now. It looks like the guy here that sells them hasn't posted since 2017. I may just have to follow your method.

Anyway... It runs again.... woohoo.


It turns out that the new BWD pick up coil was no good. I guess I should have just stayed with AC Delco parts, but the BWD had a better warranty. I know.... I know.... "You can get a good look at a t-bone steak by sticking your head up a bull's ass, but wouldn't you rather take the butcher's word for it. A guarantee is only as good as the man behind it" or something like that. You remember... Tommy Boy. :)

Craig Moates sells them along with the rest of the stuff you will need to get your rig going.

http://www.moates.net/gm-19851995-c-64.html

Ok.... I ran the Jeep for a bit while recording some data. Here is what I learned.

I don't know what I'm doing.

That said, how bout I attach some files and you guys that know more than me have a look. At right about one minute of running things start going south.

Attachment 14206
Attachment 14207
Attachment 14208
Attachment 14209

You didn't seem to get any data....... I'm sorry but you have some reading to do: http://www.gearhead-efi.com/Fuel-Inj...a-must-read!-)

I think I have some data now, I just have to find a few minutes at home to post it up. In the mean time I will share this...So I spent some more time with TunerPro RT. I really could not locate any red flags. I did get a code for the knock sensor, but that was it. Here is a short video of the software running. You will see that it stays in open loop. I am not sure if that is because I haven't installed the wide band 02 sensor yet or not. Does anyone notice anything out of place?

https://www.youtube.com/watch?v=_bt4IEINCqo


Since the software wasn't giving me a definite problem I went back to other thoughts on why it wasn't running well. I played with the timing a bit more and probably improved things a little. Then I thought I might try resetting the IAC valve. I have read on this a couple times, but never thought it could be my problem. Well shit..... I should have done that sooner. A simple procedure and it runs so much better., I played with the idle screw a bit and with the help of the Tunerpro software I could accurately set the idle to 650 and the engine is pretty happy now.

Any thoughts on this one? I was able to replay it so there must be some data this time. :)

Attachment 14249

Open loop, O2 very little variance from 450mv stoich and 2 minutes into log 20* w 4* knock retard bouncing things around. Volts seem a little low...code 43 knock sensor circuit failure.

Went back and read last 2 pages...is O2 sensor installed? How much initial timing you got at the crank? Is this engine purdy much stock meaning suppose to run on stock tune or did a lumpity lump cam get installed?

Don't know much if absence of an 'E trans causes issues, helping a buddy of mine 4.3L BJYL 700r4, found a trans error fuel cut-off parameter...so wondering myself??? Turned off a lot of trans related stuff trying to dial in tune.

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Originally Posted by stew86MCSS396

Open loop, O2 very little variance from 450mv stoich and 2 minutes into log 20* w 4* knock retard bouncing things around. Volts seem a little low...code 43 knock sensor circuit failure.

Went back and read last 2 pages...is O2 sensor installed? How much initial timing you got at the crank? Is this engine purdy much stock meaning suppose to run on stock tune or did a lumpity lump cam get installed?

Don't know much if absence of an 'E trans causes issues, helping a buddy of mine 4.3L BJYL 700r4, found a trans error fuel cut-off parameter...so wondering myself??? Turned off a lot of trans related stuff trying to dial in tune.

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Thanks for the reply Stew, You lost me a bit in the first sentence. Volts low... I replaced the alternator last night because it was not charging well. Code 43.... Wiring issue?

Single wire O2 is in place at the manifold. 3 wire O2 is on the work bench still. My timing light no longer works so it is timed to where it runs good. Bone stock 150K mile engine. I am running a Turbo350 transmission so once I can tune I will be removing all the trans stuff.

Initial spark advance in the bin calls for 0 degrees. At idle your bin is calling for 20* + whatever your seat of the pants/ear timing you set it too. Idk if that's setting off the knock retard but read on...

Imma thinkin fix the code 43 knock sensor open or grounded then clear PCM codes by disconnecting battery. From there it should switch from open loop to close loop. When in close loop that's when you'll see things like active swinging O2 mvolts, BLMs, INT, etc. as it should be. https://www.freeautomechanic.com/gm-...k-control.html

Electronic Spark Control Module is in your memcal (nomenclature?) inside the PCM. Check knock sensor wiring for open or short to ground.
http://www.gearhead-efi.com/Fuel-Injection/attachment.php?attachmentid=1921&d=1331491851

Well Stew, I have done nothing that you suggested... yet, but I did spend some time driving the Jeep this weekend. The more I drove it the better it ran. The computer must have been associating itself with all of the different components and made itself much happier. I tell you what, that 5.7 in a Jeep is pretty nutty. :)

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https://drive.google.com/uc?id=10Vfenn_c3_nME1eWUWQuJwBCU0oOjxC2

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