1990 egr problems???

MB89SC

Registered User
okay so im looking for some big time help for anybody!!!

i bought a 1990 auto sc. i did a engine swap out of a manual sc, everything was connected right except for the top of the egr cap, a small tube that looks like a hose should be connected to it?? so i am now recently aware that 1990 sc auto did not come with an egr and manual sc did..?? when i first swapped and started the car it idled good but then it would warm up and it sounded like a grinding noise coming out of the supercharger and as it stayed on running the car would struggle a little to stay running when i gave it gas it reved up nice and when it came back to normal it sounds like a cammed car but struggles to stay running.. so i swapped out the supercharger to the original supercharger that came with the car and i deleted the egr in hopes to that maybe it was also the problem. i put everything back together and the car starts up but it will not stay on. it sounds like it is cammed and dies within 10 seconds. its worse than when the egr was connected,

the engine is good. i replaced all the gaskets around the engine, everything internal of the engine is good. the car did run when the egr assembly was connected to the car but it still struggled a little to stay on but way less than it does without the egr connected.

my question is it a egr problem that is causing the car to act this way or something else? there are not any good mechanics or shops where i live that know about tbirds so any advice will help, thanks!!!:confused::confused:
 
If the EGR has definitely been removed and plugged, then the only thing remaining is a vacuum leak. Have the engine smoke tested for leaks. Most likely it's the intercooler tubes. Introduce smoke into the return plenum (where the boost gauge connects) and you'll find your leaks.
 
I can't remember the exact routing/connections, but the EGR valve is supposed to have a vacuum line connected to the nipple, routed to the EGR solenoid in the passenger's engine bay on the firewall, then a line from there routed to the inlet(?).

I'm not sure what parts you did or didn't swap around, but it does sound like a vacuum leak to me too. The supercharger noise is probably just due to some wear and the poor idle condition - I wouldn't worry about that right now.

Also, your 1990 EEC is not set-up to run an EGR system, so it won't work anyway. If the EGR valve is held open for some reason, it surely won't run well. A car's EEC with the EGR system will control the valve open/close and adjust other parameters to make the engine run correctly.
 
I'm not really clear what you have done with the EGR. If you used the auto exhaust manifold, then there is no EGR port, and the inlet plenum has a cap over the EGR port. In that case the EGR would be a non-issue.

It sounds though, like you installed the manual exhaust manifold and now are trying to deal with the EGR tube. If this is the case then I suggest plugging the rubber/silicone hose that comes up from the tube, and just leave the EGR valve itself back behind the motor. It will stay closed and will not have any impact on anything. The inlet plenum from the auto will have the EGR plugged so just leave that as is. Do not connect anything to the EGR valve.

You could also bolt the EGR valve up to the plenum if you want, but that's just extra work. In any case, do not connect any vacuum lines to the EGR or the EGR tube.

If the EGR is indeed isolated from the engine and/or disabled, then the only thing remaining is vacuum leaks. Since you said you have had the supercharger on and off, leaks on the intercooler tubes and/or collar nut are the prime suspects. I recommend removing the tubes, cleaning all flanges and removing all traces of any previous sealers, and then applying a thin yet consistent film of RTV to all intercooler joints and retighten everything. Then let it sit for 4-6 hours and try again.

By the symptoms you describe, you are definitely either running with EGR gasses getting into the motor at idle, or a severe vacuum leak.
 
thanks for the help!! i ended up blocking the egr completely and it is a vacuum. it seems to be the plenum that enters the intake manifold or the bypass valve. going to take it all apart and do as you say @XR7 Dave. thanks again!!
 
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