This car is Really Really Killin Me

[DeMasi1990]

Okay, where should I start off... I cant seem to shake this " misfire" Or whatever it May be, For those of you who dont know I rebuilt The Top end Of my 1990 Pontiac Firebird T/A. The engine is a 5.0L 305 what a few years ago was bored .30 over making it a 309. :LS1LT1flag:.. anyways.. Ive had this ongoing problem with the car Shaking to the left and to the right, kinda like two people on each side of the car rocking it back and fouth... As I write this I had just finnished replacing the fuel Injectors, as well as a leaking sheraider valve I had on the fuel rail.. She gained alllll of her power back, But is still running strange...when its cold, It really doesnt rock back and fourth, but when it gets warm forget it... All I can say is that after I put the injectors its not really as bad as it was before, and now I can hear all the injectors Ticking instead of hardly any making any sound...

Their is one thing that I havent changed that a member of this Forum said I should change and thats the O2 sensor. Its not running a service engine soon light, But I was told that It can have a weak signal.. I have the O2 and Im gonan try it tommrow, but I feel thats not the problem, Im also gonna check out the plugs aswell, with those injectors dumping like they were im sure some are fouled... a few things I want to point out are 1) its still has that " exhaust odoor" comming from the tail pipe and when the engine is running and when I lean over then engine bay to inspect things My eyes start to burn over the exhaust manifold! 2) I pulled the Number 8 spark wire off the distributor (that was a ZAP ill never forget) I noticed the ark or spark was Blue/white but it wasnt consistant, by that I mean it was kinda like ( ZAP----ZAP,ZAP,ZAP----ZAP)...tHIS DISTRIBUTOR IS NEW, and so Is the coil, Plugs Cap rotor and MSD wires. The coil is no longer attached to the engine, I forgot to put the Bracket on when I was assembling the engine again ;).. so shes resting on the valve cover for now... Idle air Control valve is new Throttle Position sensor is Original... ( sometimes she holds a RPM for a few seconds the climbs down)

We tried a New computer, and that did Nothing, so I returned it... My only Guesses are either a Vaccume Leak, Or their is a Bad ground somewhere in the engine bay or SOMEWHERE... When I did the engine I Took everything out and Re-painted the engine bay, sooo... If anyone can help me with the information provided I would be more happy then a pig in $hit.....By the way, does anyone know of any Ground wires that have anything to do with the ignition system, I plan on checking them out tommorow.. thanks guys, and Yeah, sorry for the long long post, I just need to give as much information as I can, its not like were all face to face here, lol
Walter

[t l martin]

even the best mechanics over look the obvious .my camaro had a combination intake leak and cracked vaccum line near intake. replace lines if questionable

[Stroker396@APF]

If it is a misfire it would be throwing a code to the computer and would likely be plugs or wires as the first culprits. But you did not really describe how it idles. Poly engine and tranny mounts help a lot with vibration but they will not solve the problem. You have a lot going on there. I would find someone experienced in the area that could look at it first hand.

[DeMasi1990]

If it is a misfire it would be throwing a code to the computer and would likely be plugs or wires as the first culprits. But you did not really describe how it idles. Poly engine and tranny mounts help a lot with vibration but they will not solve the problem. You have a lot going on there. I would find someone experienced in the area that could look at it first hand.



I have been speaking to a good friend of mine about the car, and I am going to bring it to a Engineer In that feild if I have te chance tommorow. I Do have the polyurythane mounths I just havent installed them yet, Im sure the mounts are shot too...Ive started the car in first gear before with the back wheels in the air and the whole dam engine whent back and Forth... I am going to look at the plugs and wires tommorrow aswell, Im sure the plugs are fouled... My car is also a 1990, and that is OBD-1.. The computer wont throw a code for a mis-fire... also the car idles fine, Only thing id did that i suspected would be the throttle position sensor because it held a rpm them climbed down

[five7kid]

Agreed, no trouble code for a misfire. Ignition, compression, fuel delivery, vacuum leak are the typical reasons for a misfire, none of which the computer would sense.

[Stroker396@APF]

If it is misfiring you will hear a miss in the idleand more so when reved up. Also do you have headers. If you eyes burn, what is it from an exhaust leak? (I thought the OBD1 codes included misfire but your right I checked and they don't have a code for that) I am not real familiar with the scan capabilities of the OBD1, but you need to isolate the problem and I would work on them one at a time. First would be to figure out the eye burning that should not happen, so figure out where it is coming from and solve that first.

[DeMasi1990]

That part where it says IGN on the fuse block, is there supposed to be a fuse there?. if so, what kinda so I know what to get, lol.. I have a feeling that this is my whole problem...or maybe not

[t l martin]

I don,t know if you talkin under the hood or dash.but if it run like that before.i'm bettin that' s not the problem. You mentioned the engine mounts... and I' wonderin when this happens if it's pullin on a ground wire.:dontknow:

[Red Devil]

Okay, where should I start off... ... The coil is no longer attached to the engine, I forgot to put the Bracket on when I was assembling the engine again ;).. so shes resting on the valve cover for now...


First I'd get the damn thing mounted properly, second I'd recheck all the 'new' parts, no telling how bad the pickup is in the dizzy and third, what about the ignition module? New? Proper heat sink goop (NOT the junk they include)? Basics first. Oh, any codes at all?

[96redlt1ta]

I looked at the GM Service manual I have for the 87', and it shows the ECM-IGN slot on the fuse block having a 10 amp fuse.

[DeMasi1990]

I dred taking out those 2 bolts in order to reinstall that bracket for the coil...So ive decided to just crack it loose just a bit, so I can slide the bracket under the 2 bolts then secure them again ( I will Cut away at the bracket so I can make this possible). I DO NOT want to remove those 2 bolts, a coolant passage is under there...If anyone thinks this id a bad Idea, let me know.. Also, I looked today at the fuse block, and A standard 10A fuse I dont think will fit in there, it looks almost like some kind of special relay goes in there, anyone know anything in reguards to a ignition fuse " IGN" On the bottom left hand corner of the fuse block for a 1990 Firebird T/A with the 5.0L TPI???

[DeMasi1990]

First I'd get the damn thing mounted properly, second I'd recheck all the 'new' parts, no telling how bad the pickup is in the dizzy and third, what about the ignition module? New? Proper heat sink goop (NOT the junk they include)? Basics first. Oh, any codes at all?



Brand New distributor with new IGN mod. And No their are No Codes Present. However Their was a aftermarket " PIGGY BACK" Chip attached to the OEM Chip in the computer, and the car was always setting off a ESC Code..We took it out and the code went away ( After reset Ofcourse)

[Chris 96 WS6]

If it is a misfire it would be throwing a code to the computer and would likely be plugs or wires as the first culprits. But you did not really describe how it idles. Poly engine and tranny mounts help a lot with vibration but they will not solve the problem. You have a lot going on there. I would find someone experienced in the area that could look at it first hand.

Pre- 1996 vehicles don't have the ability to detect and report misfires. There's no crank sensor and no codes to describe it in a 1990 ECM.

[joejoe]

it sounds like IGN, but being a TPI, dose it start good after being warmed up? if not it could be a coolant temp. sensor, air temp. sensor, but the shaking of the motor could set off the knock sensor. do you have any codes at all?? could be as simple as a crack in the air duct work going to the TB, also there are vary few vacuum lines so check them all for cracks, and make sure that they go to the right place.
ps. check the fuel pressure.

gook luck


check out this web sight.....thirdgen.org...will have all info you need

[DeMasi1990]

No its not throwing any codes... and if the shaking is there and the knock is NOT setting off a code, this may be a faulty knock sensor... Im sure that the fan switch wire and the knock wire are not confused ( i have done this before).

[joejoe]

I am not saying that they are mixed up, I am saying that the CTS could be bad. When my motor was shaking, the oil pan was rubbing the K-frame and the computer would pull timing and throw no codes...I've done this before also, was just trying to help, sorry it wont happen again.

joe

[usetaboost]

Figure your car out yet? Are you getting good pressure? Does the miss get worse if you power brake it? If there are no codes this shouldn't be that big of a deal but there may be some things you are overlooking. Start the car and spray down all the vac hoses, intake manifold, plenum, and throttle body with brake clean. It should smooth out after this. Check for loose hose clamps in between the maf. I can't remember if 1990 still had maf or not. If nothing else yet pull your iac and make sure its not carboned up and stuck. If you have a scan tool or know someone that does check you iac counts. I would definitely try swapping a known good GM maf on it. Bad mafs can do weird stuff. If you got cheapo plug wires definitely go through those. I've had bad ones out of the box.