I GIVE UP,'94 GP SE 3100 SFI LIM Repair, I GIVE UP!!!!

[KCFITZ78]

'94 Pontiac Grand Prix, 3100 with 143k. Here is the story for my car. I had an overheating problem and a loud exhaust at the same time. For the overheating problem I 1st Flushed the coollant….. that was not it….2nd NEW radiator….. helped but not it…..3rd NEW water pump…..that solved it! As for the exhaust problem I needed a new exhaust and also discovered I had a cracked rear exhaust manifold. I bought all new except for the CAT. I put the new pipes on last winter but did not replace the rear exhaust manifold. At the end of this past summer I had still not replaced the rear exhaust manifold. Then I ran into a problem. The engine started to run hot and I was losing coolant. I Looked around and found that I had coolant in the oil. Yes that’s right leaking lower intake manifold (LIM). Looked like butterscotch pudding. By the way I hate butterscotch! So for the fun part, I got real brave! Since I was going to be taking the top engine off, I took it all off. Yes the heads too. With the rear exhaust manifold cracked I figured all gaskets had been cooked pretty good plus this made it easier to pull off the rear manifold and get everything cleaned up. This is labor intensive but it went good, no broken bolts, no scratching my head, came apart nice and went back together nice. Well almost nice. I did not pay attention to the push rods. There are two different lengths for intake and for the exhaust. The correct sizes are in the right location just not back in the prior location before tear down. Once it was all back together it started, but idles really rough and gets hot really quick. It will stall once you put it gear. Also there is a knock ever once I awhile. I did pull the rods to make sure they weren’t bent and put them back and still knocks. I did not check compression seeing that it ran fine before tear down. Did not have the heads checked. Everything is torque to spec, Oil changed, filter changed, spark plugs change, all wiring checked, coolant changed, cleaned TB, no leaks, cleaned, cleaned, cleaned………………………. Any ideas what the problem is? Did I miss a step that would cause it to run like a pig and not be able to drive at all. Any suggestions? I am about ready to junk it but can’t pull myself to do it since it ran fine and drove fine before I beheaded it. I appreciate any help at all so, “Thank you†in advance!

 

 

[Brian P]

did you torque down the rocker arm nuts to spec? Also getting hot quick could be from air in the cooling system. There are bleeder screws by the T-stat and the bypass pipe near the water pump that will help fix that.

[KCFITZ78]

Everything is torque to spec (Chiliton manual for reference). It gets real hot like in 2 min so by the time it is purged i have to kill the engine, really rough idle.

[Brian P]

it's hard to say without being there what it could be. I would double check spark plug wire routing, vacuum lines (check for any hissing if you can keep it running) to start off.

[KCFITZ78]

Too much EGR flow at idle, cruise, or during cold operation may result in the engine stalling after cold start, the engine stalling at idle after deceleration, vehicle surge during cruise and rough idle. If the EGR valve is always open, the vehicle may not idle. Too little or no EGR flow allows combustion temperatures to get too high which could result in spark knock (detonation), engine overheating and/or emission test failure.....................

 

This could be my problem!

-rough idle, yes

-stalling, yes

-knock, yes (spark knock, not sure but there is a knock)

-overheating, yes

[PCGUY112887]

You mention mixing up the pushrods... did you start it with them mixed around? Doing so could have bent valves.

[KCFITZ78]

I noticed the different lenghts when i went to put them back in. I contacted the parts department at my local dealership to find out which ones where the exhaust and which were the intake. There is a flat plate about where they go and it is marked Y or G. These are colors that match the paint on the rods (of course there was no paint on my rods). Yellow is 144mm long rod and Green is 152mm" long rod. So they are in the proper location just not back in previous locations.

[KCFITZ78]

I have a 1994 grand prix se, 3100 SFI with what i think is a digital EGR. I think this EGR is giving me problems and was going to try and just replace it. If i can remove it from the engine this will help let me know if its the EGR that is giving me the problem. So my question is what all needs done to remove it:

 

-How do you disable the EGR on the chip if its the electronic?

-What holes need pluged?

-How do you plug these holes?

-Plug vaccum Lines?

-Etc.........

 

This would be a good write up!

[Brian P]

-can't "disable" the EGR on your style engine control module ('94-95 being flash OBD1) however you won't instantly get a check engine light, and will disappear upon shutting off the car and restarting.

 

Easiest way to "disable" it is to remove it, and fabricate a blockoff plate, and bolt it on the manifold (with the gasket or RTV) then remove the exhaust tube and plug the opening on the manifold. No vacuum lines since it's not that style of EGR, However I can't say this will fix your problem, but if you want to do it to diagnose it, well...here ya be.

 

Also when you say it gets hot within 2 minutes, is this just based on the dash temp gauge? If there is any air in the system it will cause the sensor to show incorrect values. I would run the car (when cold) with the bleeder valves open and wait for the thermostat to open, causing air to expel. Then kill the engine (if it shows hot), let the pressure in the system let the rest of the air out....close the valves, start her back up. The rough idle can be a few things. Make sure the MAP sensor (small black box next to the brake booster vacuum line) is hooked up correctly: electrically and the vacuum adapter.

[KCFITZ78]

I don't go by the temp gage on the dash. I can tell by the engine. Start to feel alot of heat off the engine in the air and see heat waves off the engine (this is before it got cold outside).

[Brian P]

well let me ask you, at this point does the thermostat seem open? Like is the upper radiator hose warm to the touch and hard to squeeze?

[KCFITZ78]

THE COOLANT IS CYCLING, WATER PUMP SPINS, AND THERMOSTAT OPENS. ALL WAS REPLACED WITHIN THE LAST 4 MONTHS TOO. I AM MORE WORIED ABOUT THE SOMETIMES HARD START UP, ROUGH IDLE, AND THE FACT ONCE I PUT IT IN GEAR IT WILL STALL. THE FACT THAT ENGINE GETS HOT IS NOT A COOLING PROBLEM, IT GETS HOT BECAUSE IT IS NOT RUNNING AS IT SHOULD.

[R Dubya]

LOL. I bet you rolled over a gasket or something and it has a severe vacuum leak.

 

Here, read this in detail.

To turn of CAPS LOCK, extend your left pinky finger one key to the left of the "a" button.

Now press said button.

VOILA! Caps lock off.

 

Is there any chance that you forgot to tighten down any bolts, or perhaps rolled the rocker cover gaskets, or tore the EGR gasket upon disassembly? Check things over closely. If not gasket related, I would bet the house on a crossed plug wire, they are real easy to cross up. Do you know the proper sequence? I was "an expert" when I put my TGP engine back together, , crossed the wires upon reassembly and it ran like shit until I figured it out, and it will also cause a knocking sound if it misfires. Check those, see my above advice, and then post back without copping an attitude!!!

[Brian P]

LOL. I bet you rolled over a gasket or something and it has a severe vacuum leak.

 

Here, read this in detail.

To turn of CAPS LOCK, extend your left pinky finger one key to the left of the "a" button.

Now press said button.

VOILA! Caps lock off.

 

Is there any chance that you forgot to tighten down any bolts, or perhaps rolled the rocker cover gaskets, or tore the EGR gasket upon disassembly? Check things over closely. If not gasket related, I would bet the house on a crossed plug wire, they are real easy to cross up. Do you know the proper sequence? I was "an expert" when I put my TGP engine back together, , crossed the wires upon reassembly and it ran like shit until I figured it out, and it will also cause a knocking sound if it misfires. Check those, see my above advice, and then post back without copping an attitude!!!

 

I sure hope he wasn't copping an attitude! I'll assume he just hit the caps key on accident.

[KCFITZ78]

CAPS LOCK? THAT WILL FIX MY CAR? WHERE IS THE CAPS LOCK LOCATED?

 

I will:

 

-Check the wire order again

-Check torqe on all bolts I can get to

-Check the solenoids on the EGR

-Check the value in the EGR

-Check all vacuum lines

-Check all "new gaskets" that I can see

[KCFITZ78]

Ok idle is not as rough any more, but still stalls out once in gear. Coolant is flowing good and engine does not get hot real quick, stays at normal temp. Still is not right.

 

Rechecked the following:

-Check the wire order again-------------GOOD!

-Check torqe on all bolts I can get to----GOOD!

-Check the solenoids on the EGR--------PUT IN A STOP PLATE!

-Check the value in the EGR------------PUT IN A STOP PLATE!

-Check all vacuum lines----------------READS 17" AT IDLE W/ HARDLY ANY MOVEMENT (taken @ access on manifold)

-Check all "new gaskets" that I can see-NO LEAKS!

 

Any ideas? Idle is still not right. Still has a knock that varies. Still stalls once in gear.

[KCFITZ78]

Any ideas? Idle is still not right. Still has a knock that varies. Still stalls once in gear.

[jeremy]

<----subscribes to thread

[R Dubya]

Are you getting spark on all plugs, any wet plugs?

[Brian P]

<----subscribes to thread

 

LOLOL

[KCFITZ78]

Yes i have spark on all plugs and wire order is correct. Haven't pulled plugs again but the last time there were black, don't remember if wet.

[R Dubya]

So without me having to search through everything you wrote could you please enlighten me of whether or not you changed the spark plugs? Black means rich, which means you had a vac leak or some other catalyst for running rich.

 

It's not gonna throw a code for a misfire because its a '94 (I think, never dealt with one yet). If they were black I would suggest replacement of all 6 if you didn't do it before.

[KCFITZ78]

SUMMARY OF THREAD:

 

Tore engine apart, Put engine back together (including new plugs), went to start for the first time a got really rough idle, has a knock but its not consistant and got really hot. It was then hard to start and rough idle. Checked coils, wires, pulled plugs (plugs were black) and put new in. Still no change on start up. Tired disconecting CAT, but still the same. Finally got cooling system purged, but still same. Checked torque on all bolts I could get to, checked for visable leaks, checked vaccum pressure, checked coil and wires again, still same. And last I inserted a stop plate between EGR and manifold to keep exhaust out in case EGR valve was stuck open, still same. Also has not thrown a single code during all of this and still idles rough and has a knock.

[R Dubya]

next step i would say is a compression test.. hard to diagnose over the internet. I want to know if you for sure know the plug wires are correct. Do you have a guide or are you going with the numbers on the coils?

 

 

[KCFITZ78]

I have a chiliton guide, I have also made a diagram in the book when I first ever replaced wires on the car, and as I took parts off the car (including wires) I tagged it, to insure all parts and every last bolt went back and in the correct place.

 

Side note: Coils are aftermarket and don't have numbers on them.