BadRiggins

I have a 1989 Trans Am with a 305 TPI engine matched with a 700r4 transmission.
About a month ago I took my car to a shop to get the transmission rebuilt because I lost every gear but 1st. On the way to the shop my car started to loose all power and chug there. After I got the transmission fixed the shop said that the fuel pump is bad and about to go out.
I replaced the pump in hopes that the power loss would go away, but it didn't. I don't know exactly what it could be. I also did a whole tune up on the car after that.
I have read on here for a while lately and got a list of; fuel pump, fuel filter, fuel pump relay, distributor, injectors, ecm...as what could cause the problem(s).
I bought and replaced the fuel pump, fuel filter, fuel pump relay, spark plugs, spark plug wires, distributor cap, and distributor rotor... I don't know what to try next or how to figure out what the problem is before I put a lot of money into a problem that isn't the right now.
I believe I can get the injectors for $400; (all 8) cheapest/distributor for around $250; cheapest/and the ECM will be $200-$300?
Can anybody please help me figure out what the problem is before I have about $1,000 in the car in hopes to fix the problem...!?!? Thanks for the help.

Tuned Performance

iTrader: (92)

It could be many things, bad cat. You would need to check the back pressure or pull out the o2. It could be the fuel injectors you can ohm them when the car is hot. Do you have a check engine light on ? Its hard to say u less you do some testing and or hook up a scanner to see what the ecm is doing.
If it is the injectors southbay fuel injectors has the bosch 3's for a great deal.

nomind

Agreed on the fuel injectors (from Southbay)...just put a set in my car, and it was ~$175 with 2 day shipping. I would also get a fuel pressure gauge (I think you can rent them from AutoZone), and see if its got anything to do with your issue. You may have a bad pressure regulator. From there, I would invest in a ALDL cable, and see what is actually going on with the ECM.

rusty vango

stay away from cheap "chinesium" parts

BadRiggins

I went to Autozone and bought the Actron Code Scanner for GM 1982 & higher... My car is reading codes 12, 23, 34, 44.

According to the book with the scanner they read as this;

12... Diagnostic test is working properly. (Engine computer verifies no RPM Reference Pluses are present during engine off testing.)

23... Manifold ait temperature (MAT) sensor - signal voltage is low or high.
OR
Throttle position sensor (TPS) error.
OR
Mixture Control (M/C) solenoid - open or short circuit problems.

34... Mass air flow (MAF) sensor - signal voltage or frequency is low during engine crusie.
OR
Manifold absolute pressure (MAP) sensor - signal voltage is low during ignition on.
OR
Pressure sensor circuit - signal voltage too high or low (carburetor engines).

44... Lean exhaust indication - oxygen (O2) sensor voltage stays low after one or two minutes of engine run. (Left sensor on dual sensor engines.)

How do I figure out what is wrong with the car if some codes give me more than one answer? Thanks for the help so far guys.

BadRiggins

I don't know how to check the back pressure, but I did pull the O2 sensor and the car read the same codes and was acting up the same...Does that mean that it needs replaced? My check engine light comes on randomly (seems random to me) and sometimes stays on, but other times will turn back off. I have done some research and asking around through family, some mechanics, and have been told that injectors never go bad...they just get clogged and need cleaned out; is this true? Would Royal Purple fuel treatment take care of the issue with the injectors? Thanks.

Ransford2987

Well, you have an 89, so it's a MAF, not a MAP sensor. Rule that one out. MAF sensors are the opposite of cheap, so heads up there. The O2 sensor is a cheap easy swap, so definitely go for that one. MAT sensors aren't expensive either, so I would go for that one as well. I don't have the shop manual for a MAF F-body, but this thread has a list of trouble codes. I understand you don't have a TBI, but most of these codes should be the same. I would start by replacing the MAF, MAT, and O2 sensors first; one at a time of course to see if your problem is solved.
https://www.thirdgen.org/forums/elec...s-23-15-a.html

southbay08

Injectors can definitely "go bad". Multecs for one are extremely prone to coil failure and all sorts of other problems. Once a coil goes bad, the injector cannot be repaired so you might as well just toss them, however it is true that most of the time injectors are clogged or leaking due to debris that is caught in the tip of the injector either from bad fuel or a contaminated fuel system. But yes, injectors can definitely go bad.
Some of the fuel additives do work, however it depends on the condition of the injectors and is sometimes just a temporary fix. The problem with using these additives is that you cannot visualize the end result.

www.southbayfuelinjectors.com
516-442-4707

BadRiggins

I thought that I had the MAP as a back up to the MAF, could have been misinformed... Advanced Auto Parts, can find the MAF, MAP, O2 sensors for my car and the TPS...but didn't find a MAT. Maybe I need to go in when my preferred person is in there? He knows more about these things; he might be able to find it? I'm not arguing, just trying to get the facts. Lol.

Sojer

Check fuel because all those codes relate to fuel. Put car to run (don't turn it on) put fuel gauge on it if it reads 40 to 50 its fine. Turn the car off and watch the pressure drop. If it drops fast its more or do a bad fpr but could be leaky injectors. But u would run rich and foul out spark plugs.

cwv2

If anyone that is reading this is still running the factory multi-tecs; the best thing you can do is purchase a set of the Bosch III's from Southbay. I've been running them for three years and they are flawless. I instantly noticed a crisper throttle response and the "butt dyno" told me that the car picked up a few ponies.

ragtop92

I was experiencing the same symptoms with my "92 TA. I got a pin-out listing of the
ECM and traced every wire and sensor in the car. Everything that I checked was OK with the exception of a battery + input on C16, this connection was a little flaky. This b+ is supplied by a 20 amp fuse that is located by the battery, on the radiator support. After weeks of troubleshooting and throwing a part in every once-in-a while to support a condition of self satisfaction, I went back to the basics. All of my inputs were good, all of my sensors appeared to be in the "normal" range, and my ECM was showing a 12 code, which is a self check code that usually indicates the ECM is working correctly. I had a no code situation and I had an engine that would not run more than 5 seconds. Cranks and just quits. no codes. Since the ECM monitors sensors, and all of my sensors were good, I had to look at additional problems that could cause a no run situation. The ECM does not monitor vacuum leaks, and does not monitor injector performance. So in theory, I could have a serious vacuum leak and would not have a code, as long as the o2 and map sensors were within range. I plugged all vacuum openings in the plenum and tried to start the engine. Same results, crank and stall. This lead me to the injectors. I checked all of the injectors with an ohm meter. (I had done this previously but did not, DID NOT, check every injector. I checked the easy ones and they were 16.2 ohms.....perfect. On the second check of the injectors, about two weeks later and new TPS, MAP sensor, Idle air Control, new fuel pressure gauge, fuel filter, new distributor, multiple cases of beer and a few bottles of **** Creek, I checked every injector and found 1 bad, partially shorted in number 4 hole. (passengers side 2nd from front) This partial short was not enough to blow the 10 amp inject fuse, but was enough of a current draw on the injector driver to shut it down due to high current in the ECM. This effect is what is called a crowbar circuit. One component draws enough current that it shuts off the circuit without blowing fuses. I just pulled the connector off of the shorted injector and fired the old motor right up.....on seven cylinders of course. I have new injectors, gaskets, O-rings and fuel pump rebuild kit on order and they will arrive next week.

Julie at SouthBay is awesome.

I forgot to mention the episode of the saws all and the catalytic converter. (Certified mechanic told me that the cat was stopped up.)(**** Creek helped make that decision)