I have an 89 IROC-z with a tpi 305. I think I'm having trouble with the Mass Air Flow sensor but I'm really not sure. If the car let's me start it with the MAFs hooked up, it runs like poop, it's sounds like the engine is gargled and has a hard time idling until I rev it up for a few minutes. Also, it isn't gaurenteed to start everytime with it connected. Another thing I've noticed is if I do not have the MAFs connected, as long as the engine isn't hot or flooded it will start right up. I've tried plugging the MAFs in while the car was running and it just starts gargling and dies. Another thing I have noticed is when I try to start the car without/with the MAFs after it has been running, I get a heavy smell of gas and it floods easily. I'm getting ~40psi to the rail when the fuel pump primes. ~43psi while running, ~45psi when it's reved, and about ~49psi after I shut the car off. It takes about 2-3 hours for the fuel pressure to bleed off. I'm not sure if there is a problem with the injectors because it doesn't bleed off the pressure right away.

 

Have you pulled any codes??? I pulled my 86 out storage a 2 months ago, it would start but would die right away and wouldn't idle... After running it for 10 or 15 minutes it would start to run better. Mine also wreaked of unburned fuel/rich condition. I pulled code 34 (MAF Sensor). Went to parts store and picked up some MAF cleaner and some throttle body cleaner, I also picked up an IAC (idle air control valve). I pulled the MAF sensorand thoroughly cleaned it with the spray cleaner, let it dry. While it was drying I pulled the throttlebody off the tpi assembly thoroughly cleaned it, adjusted and replaced the IAC valve and reassembled everything. I reset the computer by pulling the battery cable while I was working on it. Reconnected the battery and turned the key, she fired up and struggled to idle, swinging from 500 to 1500 rpm's back and forth, after a few minutes the idle smoothed out, nice and smooth with no more smell of unburned fuel. Took her out for a 30 minute drive and she just ran better and better. I'm assuming as the computer relearned and adjusted itself... Ran great!!! I come home fire it up about 3 hours later and it's idling erratically. Now I'm pissed off... I take her down the road spitting and sputtering and almost stalling @ a light. I get home hop on here and found a few posts telling people to check their MAF relays... So I go out swap my relays and problem solved car starts instantly, idles perfectly, and doesn't miss a beat the whole trip to work and back (40 minutes each way). Hope this helps you or someone else out. I'm ordering new relays tomorrow, they are 23 years old now, so it makes sense that they would start to fail. Sorry for the long reply...

 

MAF relays could be bad. It's often good matainence to just change them since they go bad after they age. You also need to do an injector coil ohm test with a meter.

If you have the MAF plugged in and tap on the housing with a screwdriver handle does the car change idle?

 

I never actually knew how to get the codes until today when I finally saw the write up about it.

So I checked today and I pulled code 15, 33, 34, 36. I was unaware that codes would show up even after they are corrected until I did some further research, so I disconnected the battery, let it sit, hook it back in and fired her up and drove it up and down the street for a few minutes. When I was done I repulled the codes, and I am only getting code 33 now, which is High voltage low vacuum at MAFs. So what does that actually mean?

 

It Could be either your MAF sensor($$$$) or your MAF Relays ($). I have learned the HARD way that you should replace the relays first(they're cheap and easy to do), then move on to the next if needed.

Your fuel PSI is Fine! The reason you are smelling gas, is that the ECM has codes in it and the ECM is on "Limp Mode". The ECM(computer) is sending ALOT of fuel to the engine to keep it running!

Take care of the MAF(relay or sensor) problem and your car will be back to normal!

 

You Need To Thank Chevy8588 For This Info:....

Number 87-6(Gasoline)-83 Date 1/88 MASS AIR FLOW (MAF) SENSOR SYSTEM DIAGNOSIS CODES 33, 34 AND 36 Subject: 1986-87 FIREBIRD MODELS EQUIPPED WITH LB9 OR L98 ENGINES Some vehicles equipped with 5.0L or 5.7L port fuel injected engines may experience "Service Engine Soon" lights with some combination of codes 33, 34 and/or 36 stored. This bulletin summarizes diagnostic procedures to be used in troubleshooting these codes. All 1986 model year vehicles should be updated to the latest service PROM per bulletin: 86-6G-66 and checked for "Service Engine Soon" light reset prior to further diagnosis. The MAF power relay should be checked to assure that it is part number 10067925. If it is not, then it should be replaced with part number 10067925. Please do not substitute.
DIAGNOSIS
CODE 33 (MAF SENSOR VOLTAGE HIGH)
1. Inspect to determine that part number 10067925 relay has not inadvertently been installed as a burnoff relay or incorrectly connected as a burnoff relay. (reference Bulletin 87-6G-57) NOTICE: SOME SERVICE PARTS BOOKS REFLECT THIS INCORRECT USAGE. For proper relay parts usages, please refer to the relay usage chart provided at the end of this bulletin. No substitutions, should be made.
2. With the engine fully warmed up and operating in closed loop, check the airflow at 2000 RPM in neutral using a Tech 1. If it is below 16.0 gm/sec for a 5.0L or below 18.0 gm/sec for a 5.7L engine and the block learn value is greater than 138, replace the MAF sensor. If code 33 still resets, refer to section 6E of the appropriate service manual for further diagnostics.
CODE 34 (MAF SENSOR VOLTAGE LOW)
1. Inspect the plenum side of the throttle blades for deposits. If even a small amount of deposits are present, clean the throttle body per Bulletin 87-6G-30. 2. Thoroughly inspect the vehicle for sources of air entering the engine without passing through the MAF sensor. Specifically, look for a cracked, cut or loose duct between the air meter and the throttle body, poor inlet runner to plenum or manifold sealing, a split PCV hose or any type of vacuum leak. A large quantity of air does not necessarily have to be involved. If any leaks are found, repair the condition, clear the codes and check if the code resets. 3. Check resistance of the MAF power relay contacts per bulletin 87-6G-31. The resistance should be less than 1 OHM across closed contacts. If the resistance is greater than 1 OHM replace the relay. 4. Check the minimum air rate and compare to specifications found in Bulletin 87-6G-30. If the air rate is below specifications, please reset by connecting a vacuum gauge to port A on the throttle body, increasing the air rate by turning the minimum air screw until one inch of vacuum appears on the gauge and then reducing the minimum air setting by one half turn of the screw. If Code 34 still resets, refer to section 6E of the appropriate service manual for further diagnostics.
CODE 36 (MAF BURNOFF) 1. Inspect to verify that the MAF power and burnoff relays currently on the vehicle agree with the usage chart provided at the end of this bulletin. 2. Check the relays for proper function per bulletin 87-6G-31. Also, check for PCV plugged condition per the same bulletin. 3. Check all electrical connections carefully. If Code 36 still resets, refer to section 6E of the appropriate service manual for further diagnostics.
RELAY USAGE CHART:

YEAR MODEL POWER RELAY BURNOFF RELAY 86-87 FIREBIRD 10067925 10094701 Power relay is the first #!

 

I had the same problem 3 weeks ago. I had it A Stealership for 1 1/2 weeks, (not all Dealerships are Stealerships). 3 MAF senosrs, Fuel Pump, and about $1300.00 in Tot. later, turned out to be the RELAYS........Damn that Tech

 

This is probably going to sound half retarded but, I ended up buying that MAF cleaner, sprayed my sensor and replaced it. I thought I had plugged the MAFs back in and fiddled with a few things reset CEL restarted and kept getting code 33. So I went to unplugged the MAFs and noticed I forgot to plug it back in. I cleared the codes plugged it back in and I'm no longer getting code 33. I am however getting a code 15 which from my understanding is low tempature reading at coolant temp sensor. Is this the temp sensor that is in the thermastat housing and if so I just replaced it and put in 160 degree sensor instead of the 195 degree one that was already in it. If this is the case, do I need to reprogram something to stop showing a code 15?

 

1)Did you after spraying the MAF sensor let it dry first before plugging it back on?(It needs to dry first!!!)
2)Make sure the wire is connected properly on to the temp sensor!
3)"I just replaced it and put in 160 degree sensor instead of the 195 degree one that was already in it." Senosr? Or do you mean, thermostat?
4)Changing your Thermostat would NOT cause a code 15

 

1. Yes, I let it dry
2. What wire?
3. I replaced the thermastat. Is that the same thing as the engine coolant sensor?

 

The thermastat is not the same as the coolant temp sensor. You see it here in this pick below the curved hose in the intake manifold. The brass looking item that screws into the front of the intake manifold with a elect. connector on it.

http://www.4x4wire.com/jeep/projects...8/DCP_0332.JPG

This is also a good image with diagram.

https://pontiworld.com.au/usgmsp/ima...or2139282,.jpg

 

Ahhh, okay thank you

 

OK, so know that you know where the coolent temp sensor is, double check to make sure that you didn't knock it off/loose when you changed the thermostat! Look for damage/corrosion where the wire connects to the sensor!

 

I see that youve controled the trouble code of the MAF sensor. Your car would run fine with the MAF disconnected becuase of the default setting. If one were to disconnect the MAF sensor, then the ECM would automatically return to its default setting thus allowing the car to run without the MAF sensor. The only problem resulting from a disconnected MAF would be not getting the full potential gas milage. I learned this from a member of this forum who happens to be a former GM mechanic.

 

Ahh okay, I'm still confused to why I was getting a code 33, and now that I plugged the MAFs back in I have not gotten a code 33.

 

Maby your connection was not making a good contact. Once you pulled it out (connector from the MAFs), it may of had scraped away some corrosion or grime thus exposing clean metal.

 

So is your car running fine now?

 

Nope. While trying to start my Camaro to find out why it sputters while opening the throttle, I burned out the fuel pump. I had no idea that my uncle was siphoning my gas when I wasnt around. So while I tried to start the car, he acted stupid and eventually I heard the dry whining of the fuel pump. But by then, the damamge was done. It went out after I put in some new gas. So agian I have to drop the tank. 2nd time in 3 months.

 

Be sure you make him pay for a new pump.

 

Yeah for the most part. It has trouble starting cold, and smells like it's being flooded out. My psi at the rail is good so I'm suspecting it's a leaking injector. But after it fires up the first time and I rev it for a minute or two, than it fires up every time after that until it sits for a day. More than likely I'm just going to replace them when I replace my leaking intake manifold gasket.

 

Im not going to make him pay for it. I got the 1 year warranty from Autozone. Now when the IROC is finally is on the street, then Im going to tell him something like this, "Uncle drunk, youve taken about $30 dollars of gas out of my tank, scratched my car by leaning the hood on the door, yelled at my kids for asking if you had a girlfriend, and you left my windows down during a dust storm, and took my new spark plugs. I believe thats a total of $45 dollars worth of parts that youve stolen from me. So with the $75 that your charging for labor, I believe that we can call it even considering that you yelled at my kids." I believe that'll ruin or relationship. But I dont care. the guy is a loner. my uncle is 55 years old and his last girlfriend was in high school. , he is a bum with no job.

 

Not Too Affend You But........So either he's good looking for his age OR she's a dumb ugly tool....

 

Before you go and do all that, your car Should have a "Cold Start Injector/ valve", you should take a good look at it. When your engine is cold, it acts like a primer, it could be faulty!?!?!?

 

I didn't think 89 had the cold start injector? Correct me if I'm wrong please :P

 

y84pauloflondon , I like your style man. Nah man, Im not offended. My uncle really is a worthless bum. He has no life. All he does is accept side jobs (working on cars) without pay. Im mean he'd rather be paid with a case of Budwieser. And believe me. He aint good looking at all, according to my friends. I got a picture of him in my photo album that is in my profile. Peace.

 

Neither am I, but you REALLY should look into it!!! You got a 305 TPI Right? My Repiar Manual has them listed for V6's, 305-350 TPI's

 

Who? Me? Well I got an 86 IROC Z. Now its got a 350 in it. TPI of course.

 

Cold start injector? I dont think the 89 has em.

 

Cars with fuel injected systems(V6 Crossfire, 305-350 TPI) should have a Cold Start Valve/Injector.......My book says nothing about any years being the exception to this info. (therefore all 3rd Gens w/fuel inj engines SHOULD have them!!!)

Its located on the Intake manifold just below the fuel rail(Don't know which side yet- give me some time)

 

Mine is on the driverside, next to where the PCV valve hose is located on the intake manifold.

 

COLD START INJECTORS are ONLY found on 1985-1988! Your BOOK is in ERROR>

 

Well that is why I put "SHOULD" and not "IS". Buy the way, its a Haynes repair manual. Its not great, but it is better then nothing!

 

Yeah, I was pretty positive my car didn't have one. But I started putting in new spark plugs the other week and decided today I would finish the last 3 that I didn't have time to finish, so I went outside and turn the key, let the fuel pump prime and than went and started it and it started right up. I've noticed if I let the fuel pump prime before starting the car it starts right up rather than just hopping in the car and cranking it immediately. Anyways, I pulled it in the garage since it's cold and rainy outside and noticed my CEL didn't come on. Put in the new spark plugs, car started right up, sounded 100% better and CEL is now staying off. No more code 15 now. I don't understand how the code would just go away when I didn't even do anything to fix it lol.