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Tgp exhaust leak under hood and runs rich


johnnynotell
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Hello, just got this 90 tgp and have been tuning up. Sat for a long time. It’s running rich and seems to be leaking exhaust near the egr onto the intake manifold. Looks like it’s leaking at the flange closest to the turbo also. I haven’t noticed leaking at the crossover but I’m sure it is but not nearly as bad as the other places as I see the soot. Current codes 21,43,53. TPS new, alternator new. Haven’t done the knock sensor. It stumbles/ flutters and doesn’t seem to build boost. Curious when I dig into this where can I get parts? The egr tube. Hoping to clean the egr and reuse but the tube? Also if the crossover is shot what’s the best way to go about fixing it? Take it to an exhaust shop and have them cut out the bad and install flex or hard pipe? I think I have mostly done everything tune up wise for a normal 3.1 to run fine but would the turbo run like crap because of the exhaust leaks. Wouldn’t it at least idle ok? Replaced map, tps, iac, plugs, wires, coils, ignition module, air intake sensor. Temperature sensor I got after putting back together but unplugged it to see if it helped and no. It will blow black smoke out from under hood when it’s super rich. It will kind of clear out but loads up again. Before it was surging bad. That part seems better but what else would cause this? I guess my question is would the exhaust leak make it run this bad by itself or should I replace that knock sensor first and see if it makes a difference? I have owned a 3.1 na before but it never had this problem. It had other problems that got fixed but I don’t know 💩 about the turbo 3.1. 

Edited by johnnynotell
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Welcome to the forum!

First things first, get that crossover replaced, that will cause all kinds of running issues with it. Exhaust leaks wreck how these cars run.

A point of advise, probably not relevant at the moment but I seem to remember decreasing the spark plug gap from whatever the factory recommends to help with some other running issues.

There is only one person i'm aware of who repairs those at this point. Forum member GOT2BGM aka Matt Shantz he's not on the forum much these days I'm sure he's active on the various facebook w body groups but regardless i'll shoot him a message to drop by the forum. 

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Thanks for getting back to me. I found a bad injector. It wouldn’t start. Had a na 3.1 back in the day that died while driving and ended up being a shorted injector. Also got the knock sensor out. Broke the clip though. Squeezed to hard I guess. When I get it back together I’ll post if it runs better. I think the exhaust leak is all crossover! If it at least runs better I will work on pulling that out next to have an exhaust shop fix it hopefully. If anyone still has a step by step on the remove and install of the crossover please post it if you can. All links are dead looking for this stuff these days. Also does anyone have an old chip they would sell for the ecm? Those links and people who did them are gone also. Sure would like to get some more hp if I get her running good.

IMG_0190.jpeg

IMG_0191.jpeg

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Aww man you have a wing on yours, Im looking to come across one someday.

I can post some stuff from the FSM and supplement book this evening. I`d recommend snagging both from ebay for these things.

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Code 21 = TPS sensor circuit

Code 43= ESC (electronic spark control) circuit

Code 53 = system over voltage.........occurs when the ECM sees an ignition fuel reference of more than 17 volts.

 

 

 

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Thank you guys for chiming in. I do need those to diagnose better. The fuel injectors are coming and I did replace the alternator for the high voltage. I must have code 43 wrong 55 trucker. I came up with knock sensor error. I will look into it better. Nice to meet you Rich with the tgp. Not to look too far ahead but how did you go about fixing the crossover? I plan to remove it and take it to an exhaust shop and have them do their magic. Thinking I should buy a couple of these flex pipe things. Not sure the diameter of the pipe yet though.

IMG_0247.png

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A repaired crossover will look like this.....

image.jpeg.0566950676a27bf80dfcab5245863555.jpeg

I don't personally know where the turbo flange gasket is available from anymore.

Where your *lack of boost* issue is concerned remove the actuator arm from the wastegate valve & try to move the valve lever. It should not be seized.

Now test the pressure diaphragm inside the dashpot using a simple handheld vacuum pump to see if the diaphragm has not failed, you're looking for no loss in the reading on the vacuum gauge. The wastegate is normally *closed* due to a return spring inside the dashpot. You'll need to test the wastegate solenoid as well, the solenoid is also closed by default which causes the boost pressure from the turbo to open the wastegate to reduce boost pressure to the engine.

Sort out your DTC's first, the turbo wastegate being open shouldn't upset the engine at idle as the wastegate is open at idle, as long as the engine is running the turbo is supplying various amounts of boost.

 

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5 hours ago, johnnynotell said:

Thank you guys for chiming in. I do need those to diagnose better. The fuel injectors are coming and I did replace the alternator for the high voltage. I must have code 43 wrong 55 trucker. I came up with knock sensor error. I will look into it better. Nice to meet you Rich with the tgp. Not to look too far ahead but how did you go about fixing the crossover? I plan to remove it and take it to an exhaust shop and have them do their magic. Thinking I should buy a couple of these flex pipe things. Not sure the diameter of the pipe yet though.

IMG_0247.png

Fortunately my crossover pipe still seems in good to ok shape for now but its something Ive looked into replacing for sure. Going by the supplement the crossover comes off without any specific instructions really aside from rotating the engine to get at the "rear" of the engine.

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Possibly, the turbo is a Garrett T25/28 series...

 

do a search for the turbo flange gasket for that model turbo, I'd imagine that they are still a common item. I've been out of Chrysler turbo cars for some time now.

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That's a good looking TGP you have there. I don't have a TGP, my Grand Prix is from '96, but red with the spoiler is exactly how I would want mine.

Edited by Amanita
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On 5/11/2024 at 8:30 AM, rich_e777 said:

As for impossible to find exhaust gaskets, could this Fel-Pro stuff be cut to fit?

https://www.jegs.com/i/Fel-Pro/375/2499/10002/-1

LMAO, I meant to post this on another forum discussing old lawnmowers! They dont know what I`m talking about over there either.

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Posted (edited)

Hey guys, not sure if I’m replying correctly to these. First things first. Nice engine! Next, thank you for the schematic… Lastly I’m down to code 43 and 53. Knock sensor is new. It’s not running properly. Is smoother now but am curious if you guys have the magic fix? Thanks again for all the helpful information.

 I got some dielectric grease and electric cleaner. I noticed gm had a bulletin to clean and grease the wiring harness connector. I assume to the ecm. Probably should do all the connector’s I can get to. Could be bad ecm if it doesn’t help.

the fan kicks on at weird time’s also. Something electrical is not letting it run right. High idle still also. Iac new.

Edited by johnnynotell
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Try not to give into the habit of *throwing money at the problem*. Purchasing unnecessary part is a waste of money........

The code 43 may not necessarily be the knock sensor itself but an issue with the harness or possibly the ECM.

Seeing as you have the code 53 (system overvoltage) if you know beyond a doubt that the alternators regulated output is approx 14.2 when the engine is running then the ECM could be the source of the issue.

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Yes it’s getting expensive already. It did sit for a long time so I didn’t mind putting some newer parts on it. I would guess it was all original stuff on it. But anyway I ordered an ecm. I’ve addressed all of the codes it was throwing and 21,43,53 keep coming back. New iac, new knock sensor, new alternator. Still high voltage errors. Sounds like there is an internal voltage regulator in the ecm that can go bad. I tried cleaning the ecm connectors and no change. Runs nice until the ecm takes over then the codes pop up and runs erratic again. I will update after install. 

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  • 2 weeks later...

It was the ecm. Codes would keep coming back and stalling 

on to other problems. Would love to find a chip if anyone knows of any available. Still need to fix the crossover and the brakes work but the light is on and the abs runs every pedal push. Found the place in Pittsburgh who can rebuild for 950.

going to do the transmission fluid next. It shifts super firm. Only in the higher rpm’s but didn’t expect that. Works good though. 
 

can feel the turbo now. Another thing the ecm wouldn’t let work. I hope a chip would let it get a little more. I don’t know if the leaky crossover would mess with that or not? The psi in the manifold. I wouldn’t think so but I don’t know 💩thanks for helping and hopefully this can help someone out someday.

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On 5/29/2024 at 1:06 AM, johnnynotell said:

It was the ecm. Codes would keep coming back and stalling 

on to other problems. Would love to find a chip if anyone knows of any available. Still need to fix the crossover and the brakes work but the light is on and the abs runs every pedal push. Found the place in Pittsburgh who can rebuild for 950.

going to do the transmission fluid next. It shifts super firm. Only in the higher rpm’s but didn’t expect that. Works good though. 
 

can feel the turbo now. Another thing the ecm wouldn’t let work. I hope a chip would let it get a little more. I don’t know if the leaky crossover would mess with that or not? The psi in the manifold. I wouldn’t think so but I don’t know 💩thanks for helping and hopefully this can help someone out someday.

On the TGP facebook group find these 2 people

 

Matt Shantz to buy a rebuilt crossover

Adam Perkins for your ECM chip

 

These are the only people who do that for the TGP community with the experience you'd want.    

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Posted (edited)

Thank you thank you for yours and everyone’s help. It is greatly appreciated. 
I had no idea there was a Facebook tgp group. I will be checking that out thoroughly. Anyway here’s a picture of my old Grand Prix. It was the reason I even knew about the tgp. I thought I knew everything about gp’s at one time. But I didn’t and still don’t. 
69 sj  I still regret selling it.

IMG_8868.jpeg

Edited by johnnynotell
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