K.C.Kustoms

Hello,

I have a 1991 Firebird V6 that has been giving me major issues for over 2 years now.
First off we are having problems getting it started. When you let it sit for a couple of days it will be able to start but after that first start it will not be able to start again for another couple days.

When we do get it started you have to press the gas pedal to give it more gas for it to start up, when it does start and begins to run you need to keep your foot on the gas and keep the RPMs at about 2000 or higher or it will just die out. But after having it running in the way stated above for about 10 minuets it will just die out completely and not be able to start for a while.

Also, when it is running the smell of the engine and exhaust smells like it is burning really rich. But it also seems that it is starving for fuel. When we pulled one of the spark plugs you can see that it is a charcoal color.

Now in about September of 2010 (last year) we decided to try and fix these problems. Our code reader gave us these codes:

33. High voltage (low vacuum) at mass air flow sensor (or MAP sensor)
43. Low voltage at electronic spark timing circuit
54. Low voltage at fuel pump OR Low voltage at Fuel pump relay OR Output failure at quad driver module.

We got some suggestions on how to fix these problems last year.
Here is the link to my previous postings - https://www.thirdgen.org/forums/v6/5...code-help.html
Last year we replaced the following:

1. E3 Spark Plugs
2. Fuel pump relay

These did not fix any of the issues and we did not have the funds to continue at this time.

K.C.Kustoms

This year we decided to tackle it again.

We started off with the same problems that it had before.

The codes were now only:

• 43: Electronic Spark Timing (EST) circuit - low voltage detected. OR Electronic Spark Control (ESC) - circuit problems.
• 54: Low fuel pump voltage. OR Fuel pump relay. OR EGR Solenoid No. 2 failure. OR Quad-Driver Module (QDM) output failure. Or Mixture Control (M/C) solenoid - circuit voltage too high.

~I did disconnect the battery before testing it again so it would have been reset and new codes displayed.~

We decided to replace some things our selves to try and cure these problems.

1. Fuel Pump
2. MAP sensor
3. ECM

We replaced these all one by one testing the car after each one. They all had no effect on the way the car preformed. It still had the same issue starting and the same issue of staying running. It also gave us the same codes of 43 and 54 after resetting them again.

We really need your guys help. We are not sure where to go from this point and need your input.

Do you think it is the fuel filter or VATS? I don't think it is because the security "Dummy" light does not stay on when it is running.
My buddy's had this same problem and when he replaced his fuel filter it worked again. But I don't know.

Thank you for your time.

Base91

iTrader: (1)

Have you tested the injectors?

K.C.Kustoms

No we have not. And I'm not really sure how to do that.

Could you describe how to check them?

Thanks.

Base91

iTrader: (1)

You need to take off the top part of the intake system. Basically unbolt/disconnect things until you can remove the upper plenum. That exposes the tops of the injectors. Remove the electrical connectors and measure the resistance of the injectors with a digital volt meter. The resistance of all should be about 13 ohms and all about the same. If any are significantly different they are bad. In which case replace them especially if they are old. Even if the resistance is good they may still be clogged. If you don't have one you should get a Chilton manual. It has a bunch of info on how to test this stuff.

Maverick H1L

iTrader: (8)

Um, no.

First, if he's going to get any manual, he should get a Helms factory manual. Chilton's is lacking and Haynes is just plain wrong, end of story. Plus they can be had for about the price of Haynes if you know where to look.
Second, you don't need to remove ANYTHING to test the fuel injectors. There is a 6-pin connector next to the thermostat housing. Disconnect it and probe the terminals (pink and pink/black to blue and green, not yellow and black, which are for the CTS). Resistance should be 4 ohms (or thereabouts). Any more or less indicates a short either in the wiring or an injector. Then check each individual injector if a problem is found.
Last, the ECM can't differentiate between the EGR solenoids and it does NOT have a QDM. Nor do you have a mixture controller, as you don't have a carburetor.

Now, after you test the fuel injectors, I would check the resistance of the CTS, and measure the MAP sensor voltage with the engine running (between the green and black wires). Oh, and swap the fuel pump relay with the one next to it for the radiator fan. You didn't need to replace the fuel pump, as that wasn't an issue. Code 54 indicates a problem in the power side of the circuit, between the fuel pump relay and the oil pressure switch, which is actually running the pump instead of the relay on your car (and it's not supposed to). Oh, and you may want to get your hands on an ignition module (just in case) and definitely replace the ignition coil (if it's the original, it's probably worn out).

K.C.Kustoms

Thank you all for all your help. I will get right on what you said for me to test.

Yesterday, I tested all 6 injectors with my ohm meter. I have a picture of what our readings say.



They were all around 12.6 is this ok? or should I check that 6-pin connector by the thermostat housing?

I also have a few pictures of my engine bay. When I first bought this car I notice that some wires were spliced here and there and some hoses were plugged with (screws)! I have no idea why or where these lines go maybe you guys could help. Also, I'm not really sure which engine I have I know its a v6 but don't know to much about what type it is.



If you notice toward the back of this second engine bay picture you will see a screw in the black hose coming from the back left of the intake and from the back right there is also a small red hose that has a screw in it. What in the world are they for?



On this last picture toward the back of this pulley you will see a green wire with some tape on it. Why is that?



As you can see this car has had some weird things done to it by the previous owner some of which I have no idea why. But I do know it was running when we bought it.

Thank you all for your help and I hope that we will be able to get this thing running very soon. I will update you on any of the test we will do.

Maverick H1L

iTrader: (8)

Injector readings above 11.8 ohms are GM spec, they're fine. Also check the injector harness as I indicated due to possible problems in the harness.

Check to make sure you have a vacuum signal to the MAP sensor, should be a line connected to it and the nipple in the back of the plenum in the left corner, not at the T that's plugged. What went there was the vacuum source for the cruise control and for the heater controls. There is a sticker attached to the bottom of the hood. Follow it and rebuild your vacuum hoses accordingly. The sticker may be covered with grime.

BTW, your engine is a 3.1...

K.C.Kustoms

Sorry I haven't posted in a while but I've been pretty busy at work.

Anyway a few days ago (The 13th) I decided I would test the things you told me to test I tested the injector harness and the CTS they were both fine.

So, I decided I would switch the "New" fuel pump relay with one of the "older" ones that were by it just to see if the new one was bad. And to my surprise the firebird started up and it idled it was a very rough idle and it seemed as though the engine wanted to cut out but it kept reving it's self to stay alive.
This went on for about 20 minuets. So, I decided to shut it off and restart the process to see if it was just a freak thing that happened. But the engine poped right on and did the same thing it was doing.

I then plugged my code reader in to see what the codes were.
It read:

• 33: Mass air flow (MAF) sensor - signal voltage or frequency is high during engine idle. OR Manifold absolute pressure (MAP) sensor - signal voltage is high during engine idle. (Note: Engine mis-fire or unstable idle may cause this code.)
• 43: Electronic Spark Timing (EST) circuit - low voltage detected. OR Electronic Spark Control (ESC) - circuit problems.

Code 54 was now gone. But 33 was back and so was 43.

Any idea how to fix this rough idle problem?

I took some footage of the Firebird running with its rough idle so you could see how it sounded. Maybe it will help.
Here's the link - http://youtu.be/GMFgqQndEOE

K.C.Kustoms

The above post is what happened on the 13th.

The next day on the 14th I decided I would try it again making sure it would do the same thing. But when I started it I had to push down on the pedal to give it more gas until it started. Then you could see the rpms start to lower as the engine was going into its idle all of a sudden everything just shut off. The engine, all of the lights every thing. It looked like a fuse blew or something electrical went wrong.
When I tried to turn the key nothing went on no ACC, no power to start, nothing just everything silent.

I have no idea what happened it was not the battery because that was charged and I had the charger on the car not to mention I put the charger at 50 amps "Start mode" which usually starts it when it has a dead battery but still nothing.

I thought it was a fuse so I checked all the fuses under the dash but none of them were blown. I think that there might be a ground wire lose some where but I really have no idea what happened.

This is pretty frustrating considering it was running and idling the day before. Any ideas on how to fix this problem now?

Thanks for all the help you guys have given me and thank you Maverick H1L for all your amazing advice.

Maverick H1L

iTrader: (8)

Need to replace the fuel pump relay...

Still need the actual resistance of the CTS to compare to a chart of temp vs resistance (and the air temp with the engine cold). The resistance changes with the temperature of the sensor. The chart has been posted here any number of times. Also, there is a similar sensor in the air filter can. Compare the readings. The CTS and the IAT (intake air temp sensor) should have pretty close to the same reading if the engine hasn't been run and all is cold.

Check the connections on the big terminal of the starter with the battery disconnected. If the nut isn't tight or there is corrosion, everything dies due to no power. Also check to make sure that the wire coming out of the harness near the ignition coil (should have a tan/black wire on it, the white one is for the tach and won't help) has both halves attached (inline connector that is split to set timing). Should get rid of the code 43 unless there are other problems.

southbay08

just because the ohm readings were within reason on the injectors does not mean that they are functioning properly. Checking resistance/ohm just gives you info about the coil. There is still a chance that you have one that is leaking or clogged. If you want to do a quick check for a leaking injector, run the engine for a minute or two. Then pull the plugs, if you have any wet cylinders then you have an injector that is leaking. If you want to go the next step, send the injectors to us, we will put them on the bench to check them, NO CHARGE, if there is an issue we will let you know and then we / you can deal with your situation accordingly.


www.southbayfuelinjectors.com
516-492-6504

Six_Shooter

iTrader: (2)

The '7730 ECM most certainly DOES have a Quad Driver Module, I'm just not entire sure what ir if anything is driven by it in this application.

A worn fuel pump can cause excess current draw which in turn can cause what is read as low voltage in the circuit, so even though the fuel pump may not have been the entire issue, it certainly hasn't hurt anything by replacing it and pretty much eliminates it as a problem, almost.

I would test the fuel pressure itself using a proper gauge. Use a DMM to verify actual voltage in the fuel pump circuit, sometimes the circuit running the pump is fine, but there might be a problem with the short splice that runs to the ECM that monitors that voltage.

I don't know why people knock the Haynes and Chiltons manuals so much, I find them to be perfectly fine, especially for the average DIYer. I use them for reference if I can seem to remove a part, or for torque specs.

With the lack of power at all, this could be related to the low voltage in the fuel pump circuit code you're getting. There could have been a corrorded or almost burnt through fuseable link (at the starter), that has now failed and won't allow any power to the car. Grab a DMM and follow the electical path until you don't have voltage and between the points you do have voltage and the point you don't where your problem lies.

K.C.Kustoms

I know its been a while since I've updated this thread but I started up on this project again due to the fact that it has cooled off outside and is much more bearable to work in.

Anyway, pretty much I fixed the problem with the electronics not working. All it was, was a plug by the starter that had been pulled lose so I just plugged that back in and now it turns on fine again.

After I let the battery charge because it had been sitting for awhile it started right up as it had back from 2 months ago.
But the idle is still incredibly rough and I have no idea why.

Also, it is still giveing me a Code: 33. but no other codes.

Any ideas how to fix this "Rough Idle" along with "Code 33"? Could it still be the fuel injectors?

Thanks for all the help guys, it has been so useful to me!

Base91

iTrader: (1)

You could start by testing the MAP sensor. You'll need a digital volt meter some wire and a 5volt electrical source. You can use the USB port of a computer. There are instructions somewhere in TGO or Google them. Check for vacuum leaks and the line from the plenum to the MAP. But if the injectors are old and/or you don't know their history take up the offer of a free check up.

oldPontiacOwner

----------
The above is correct. I only wanna inform you of a weird little situation I ran into just measuring ohms.
My #4 injector measured the same as the rest of the injectors: about 12.5 ohms.
The bad symptoms were a rhythmic misfire, i.e. never random and always in the same sequence as a "whoosh" sound from the exhaust with the rest of the cylinders as a normal tone at idle. The engine shook with increased rev's as expected, and power was diminished.
Since all 6 injectors were fresh rebuilds, my brain refused to accept one being bad. But since engine misfires from ignition problems are usually somewhat random, I tested the injectors anyway.
Of course, you have to reveal the injectors and fuel rails by removing anything on top, like the intake plenum.
Then I removed the fuel rails with the injectors still in them, and left the fuel lines connected. I disconnected ALL the injector electrical connectors, and placed a wad of fresh paper towels under injector #1. I then reconnected ONLY injector electrical connector #1 to injector #1, and turned the engine over a few times. The paper towels then had spot of fuel on them telling me #1 was good enough for this test. I repeated on each individual injector.
The #4 injector was bad even though the resistance was good. With the #4 connector connected to the #4 injector, no spot of fuel was found on the paper towels. I used the #1 connector in place of the #4 connector, and still no spot of fuel appeared on the paper towels.
I replaced the #4 injector and reassembled the intake area, and the engine ran fine. Please use a torque wrench especially on the intake plenum bolts. My spec indicates about 20-22 ft lbs, i.e. just beyond snug. Be sure to follow your manual's spec. Past that, the bolt head will break off to protect the aluminum. Guess how I know.
Some WARNINGS: OF COURSE, don't smoke or allow anyone around you to smoke while doing this procedure. Also, before removing an injector, depressurize the fuel rail using a connector/hose that fits the threaded pressure measurement connection into a quart catch jar. NOT DOING SO may cause about a 1/2 cup of gasoline to drip into the injector hole(s) in the intake manifold, filling the cylinder if the intake valve is open, or draining down into the crankcase/oil pan making an oil change necessary before doing anything else. If you don't change the oil or remedy the cylinder filling up by removing the spark plug, the piston may top out and destroy the engine or at the very least the cat converter may be destroyed. There are other big problems that could happen that shouldn't be ignored either, like main bearing damage from lack of proper lubrication.
In any case, good luck with it!

willexoIX

4 years later :facepalm:

MadMax32781

Hello,
I know this is an old thread, but my 1992 Camaro 3.1 V6 started doing the same thing that K. C. Kustom's Firebird did.

Question for K.C. Kustom. Did you ever get your car running? If so what was it that fixed it?

Drake Duncan

Could you send me a picture of what you needed to plug in. I have exact same issue and previous owner also did some crazy things under the hood

Charles Holdren

When it is dark enough, have the hood open and start engine. Look for sparks coming from your spark plug wires. If you see sparks replace spark plug wires. I call this the firework show. Also under the distributer cap there is an ignition control module (ICM). Remove this and take it to Autozone for testing. If it fails replace with a new one with the lifetime warranty. While the cap is off, using a dremel with a tiny wire wheel, carefully remove and rust from the 12 contact points on the star type electronic ignition. Make sure to clean all dust out before replacing the cap and rotor. Other ideas might be oil pressure sensor failing which is ran through the fuel pump relay causing intermittent fuel delivery.

cosmonautpg

Just a quick note — I had a really rough idle problem on my 3.1 about a year ago and found a massive vacuum leak on the small-ish hose that runs from the top down to the AIR pump. It looked like wear/heat had burned a a hole in it about 1 cm — I was able to find it by tracking down a “swishing” sound that would come from the engine bay.

After replacing that as well as some very brittle hose running to the vacuum reservoir (the long one that runs around the outside of the bay) it pretty much cleared all idle problems right up.

Not sure if this applies to anyone tracking this thread’s problem but I figured it would mention it!

Onegoodone79

It's about time I See some critical information that is CORRECT.