jamesbob02

Pretty much like the post says....the car began running crappy a while ago and has been over heating. I upgraded ignition parts.....nothing. Noticed exhaust manifold glowing in front of #5 cylinder, so I assumed injector or valve problem. Checked valves - good as normal, replaced O2, checked TPS, IAC, replaced PROM, everything's good. Decided to replace injectors w\ Ford 19lb/hr's, which should be about 21lb at GM pressure, near 22lb stock. Replaced them, nothing - runs worse maybe (week between running before and after swap). Sounded good in park, revving engine - assumed everything great and went to drive....no power. It'll drive, but is incredibly slow. The RPMs climb really slowly. When I can get it up to 3500 or so, I can begin to feel the power, but it still doesnt go fast because it still climbs slowly. What should I do?

Notes: I have not yet done a compression check, but will. I was afraid that I put the newer injectors in wrong, but looking back, I can't imagine how - it was pretty straight forward.. I dont know if there was supposed to be any sealant on the intake gaskets but there wasnt any when I took it apart so I didnt put any on them - the engine was rebuilt in the last year by someone else so the gaskets were in new condition basically. I am willing to go back over the injector swap steps if necessary to check something or to put sealant on, but I'm looking for tips I can't think of. I'm pretty sure the timing is on, I lined up the rotor, the valves, TDC, and the mark on the crank without any trouble. What should I check now? Thanks guys.

87Formula4bbl

There shouldnt be any sealant on the GASKETS, but has to have RTV sealant on the two (front and back) 'cross sections' between the heads, on top of the block. If not, it would suck air like a mother. But I'm sure this isnt the case, right? Hehe.

jamesbob02

I'm not sure where you're talking about, but I dont think I went there for the injector swap, I just took it down to the base (only took off the plenum and runners, not the base)

Morley

How's your cat. converter? Sounds like a plugged converter, it will run good without a load, but with a load the engine just can't breathe, overheats and causes manifolds to glow.

jamesbob02

No cats. Thanks, though. Anything else?

2.73's Suck

you probably checked it already but it sounds like your timing may be waaaay retarded, that would make the manifolds glow too.

Mgilb18

Hey James, I am not expert but can only tell you what I have experienced. My trans am has been experiencing the same thing lately. It has been hesitating badly under acceleration, runs hot, starts really rough when cold. I've tried many things to remedy this and spent a lot of money. Finally I broke down about bought a new ecm. I saw that you replaced your prom. After I replaced my computer, the difference was night and day. I kept my same prom being that it was one from Hypertech. The car now runs great. I ended up getting mine from a friend that works at a dealership, not sure if you have that luxury. If not you might expect to pay 300-350 for one. I know that my local autozone had them for like 90 bucks or so. They are remanufactured but then again so is the on I got from the dealer. I would imagine you would be ok getting one from an auto parts store. Just be sure that you are getting the correct computer (one for a TPI). Just a thought, it worked great for me. 2.73's is right thought about your timing, if you are sure that it is correct, your ecm could be the prob.

jamesbob02

Mglib18 - Thanks for the long reply; your experience is exactly what I was looking for. Honestly, I think its the computer, too. I question all the things I've done on it but, realistically, I can't imagine what I did wrong. I forgot to mention - I installed a fuel gauge and the pressure seems to be fine, so I dont really question the pump. I'd tell you what the knock counts are and what the fuel mixture's like but I can't get my ALDL cable to work yet.

Even though I believe it to be the computer, I'm starting to wonder about the transmission. It went out a few months ago and was rebuilt by a shop we trust completely. It didnt shift like I wanted it to so I took it back and they put a valve body assembly (and governor, or whatever) from a police car in it. I love how it shifted after that, and that was less than two months ago. The car has been driven very little sense then, though, because of the running problems. I dont know enough about tranny's to know, but is it possible that something from the tranny backward is just slowing me down all of a sudden? I mean, the car just runs great in park but crappy under load, so I dont know.

I know this is getting complicated, but I really like what I learn from all you guy's experience. Another thing I'm worried about is that I was questioning my programming, so I had a new chip burnt. However, I only realized later that the computer reuses half of the old MEM-CAL, which I dont trust. Apparently its the fail-safe and knock system stuff that is still used, or something like that. Should I be worried that just my MEM-CAL is causing this or is that impossible?

Thanks guys - I know this is long, I hope some of you read this far and can comment!

Mgilb18

It's funny you say that about your transmission. My car is in great shape, I really try to take care of it. At about 94,000 miles my transmission was rebuilt too. Just like you, after getting it back I didn't like the way it shifted. The transition from gear to gear was too smooth, before you could "feel" the shifts. They put a much stiffer spring in my my valve body controlling the shifts from 1st to 2nd and 3rd to 4th. It made a huge difference. This work was done at a reputable place as well and costed me about 1600. I have a warranty and am beginning to wonder if I'm having troubles with my transmission again. I took it to a shop and they tell me that my torque converter clutch is slipping in and out. This really only happens right after the car shifts into overdrive (around 45-50 MPH). It is sort of like a chugging or surge type feeling. It still does this even after the computer swap. I'm thinking I'll have to take it in. I really doubt that there is a problem with your transmission that is making that much of a difference in how the car drives. If there was, there would more than likely be some huge deterioration between parts in your transmission. It probably wouldn't be working anymore.... Another thing you could maybe try would be your mass air flow sensor. Not sure what year your car is. I know that the mass air flow sensor was taken off and converted to a speed density system at some point. Anyhow, a few years back my car ran great in park, as soon as I put in in gear and stepped on the gas it would die. There are 2 relays for your mass air flow sensor. One is a power relay that does just that for the sensor. The other is a burn off relay. After the engine is shut off, (or right when it is started) not sure when, this relay heats the wire in the sensor that senses the air to some really hot temperature to burn off an residue that might have built up on the wire. If this process isn't happening, the wire that senses the air in the sensor isn't clean and could be giving faulty readings. Both of these relays are the same part number and both are cheap to replace. I have a diagram as to where they are located if you need it. You could always swap the two and see how the car runs. If one of them truely is bad, it should probably either run really well, or die when you put it in gear. If one of these two things happens after being switched, replace them. The sensor itself could be bad, I don't know of any way to test it. They are like 80-100 bucks after core charge at a parts store. A little expensive to try if you don't know.... but so is a computer. I would say that if you service engine light isn't coming on, then your sensor probably isn't bad. Just food for thought.

jamesbob02

I have a speed density car - 92 350 TPI. Since what you said, though, I wonder whether or not my torque converter is working properly. Its possible that this could be the case, yeah? Since it runs good in park but not in drive with no codes I figure it could be. Has this happened to any of you guys?

jamesbob02

I replaced the computer and it didnt do anything. I'm gonna try a new Mem-Cal. I DID get a new prom but I used a Moates adapter that re-used half of my old Mem-Cal, so I dont completely trust it. Any other suggestions? Thanks. -Jimmy