hokiefanatic93

my 87 camaro has been running pretty rough lately and occasionally stalls out when idling. the only code is get is 34 ("low voltage (high vacuum) at mass air flow sensor (or MAP sensor)) what could are causes of this error? thank you.

Base91

iTrader: (1)

First check all hoses for vacuum leaks. Check connections and grounds. Then see where you are.

hokiefanatic93

i couldn't find any vacuum leaks and i checked alot of the connections. Could it be the mass air flow sensor? is there a way to test it?

hokiefanatic93

could the failing MAF sensor explain why my car stutters and bogs down when starting from rest?

hokiefanatic93

i found a small vacuum leak i just repaired. hope this fixes the problem. thank you.

camarosrock1989

iTrader: (1)

Did that fix your problem? was it the vacuum leak? I am having the same problem, was thinking about changing out the MAF.

hokiefanatic93

It didn't really fix the problem. it made my car run better though. it stalls out alot less then it use to. now it normally seems to only stall when switching between reverse and drive or when giving it the lightest amount of gas then letting off the pedal. overall the vacuum leak fix seem to help smooth the car out so it doesn't run as rough, but it is still stalling out on occasion. i debating on whether i should replace just the MAF or the TPS. or if i should replace both.

hokiefanatic93

and it still bogs down/stutters when the car is still warming up when moving from rest so i'm thinking it can be the TPS

ziggy714

i,m having the same problem....let me know how u fixed it.

hokiefanatic93

the code just went away when it got cold out. now we are having some hot days and it came back and my car bogging down again. so whatever is causing it, it is related to the temperature outside.

OUR_ZED

1988 Camaro Service Manual discrepancy on M.A.F. relays and Fuel Pump Relay location.
"F" series, RPO: LB9 & L98, VIN CODE: F&8, 5.0L&5.7L, V8
page, 6E3-A-2 5.0L; top view master cylinder to fender (DS) "M.A.F POWER, FUEL PUMP, M.A.F. BURN-OFF" (NOTE: there are 2 pages with same number "2.8L & 5.0L"
page, 6E3-C1-7 5.0L; fig. C1-11 contradicts above and shows SIDE VIEW MASTER CYLINDER TO FENDER (DS) "M.A.F BURN-OFF,FUEL PUMP, M.A.F SENSOR (POWER)"
My 1988 IROC Z28 (owned since new) has this original factory relay information: L to R, #14078907 (8123) rectangular relay/connector, #14089936 (1298) oval relay/black connector & # ??? oval relay/white connector.
Now I have read the continuing saga about these relays and their numbers, now is there anyone who can explain all the discrepancies? It would seem each year 87/88/89 has a difference on the 5.0L & 5.7L TPI, not sure about 90/91.
I two have a "code 34" come up continually since new, dealers/mechanics/myself have tried to fix and always went back to original relays. ECM has even been replaced.
My S.E.S. light comes only after warmed up, shut-off restart "ON", drive no shut-off "ON" then maybe "OFF", only noticeable difference "hesitation on acceleration" and richer fuel use. Note car is only occasionally used in summer then stored. Wiring and hoses have been checked and are OK.

Ray the Rat

iTrader: (1)

I'm getting a 34 code, too. It started sometime over the winter. I don't think it was associated with anything. But the MAF sensor's new (9 months old, I guess), so's the IAC (brand new), for that matter. I've cleaned the new MAF, checked for vacuum leaks but nothing seems to change it.

I wasn't able to read the code until I swapped ECUs...at least I can read 'em now.

The other problem I'm having is a high idle. I know it sounds like a vacuum leak, but I've just gone thru 2 cans of carb cleaner and now I've got one of the cleanest motors ever in a beater-mobile (I really like the car, but it IS pretty beat up and I use it as my economy car) but if there's a vacuum leak there, I can't find it.

One thing I haven't done is adjust the TPS voltage. Could this affect the MAF output? I wouldn't think so, although I'm sure it could affect the idle.

tia

Maverick H1L

iTrader: (8)

First, check the TPS voltage between the BLUE and black wires. If it's not .55V, make it so that it is by adjusting it if possible. Reset the ECM by either disconnecting the battery or taking out the fuse on the passenger's side, that's bolted to the frame rail, with the ORANGE AND RED wires. The other is for the MAF.

Second, if that fails, remove the MAF relay and swap it with one by the brake booster. Also check the MAF fuse next to the inline fuse for the ECM constant power and fuel pump. Reset the ECM and see if the code comes back. Also check for 12V at the MAF connector, orange wire, with the key ON.

Third, failing both of the above, remove the MAF (this is especially true in the cases of NEW AFTERMARKET MAF sensors). Look into the engine side of the sensor with a light reflecting off of the orange film inside. If the film doesn't appear to be completely flat, the MAF is toast and the only way to fix it is to get a new one. I HIGHLY recommend a GM MAF. I've had 2 aftermarkets and NEITHER was made right. The second one failed in ONE YEAR, and I never had an air leak. While checking the MAF, make sure that each and every component in the air intake is sealed to the next (especially true with Bird intake cans), as any air leak, even a tiny one, can kill a MAF.

GM p/n's 25007557 or 25007668.

Or, the easier way is to get your hands on a meter that will test frequency... The 2.8 digital MAF is supposed to put out a frequency of approximately 32Hz at idle.


ZED, your car doesn't have the same system as the 2.8. It has 2 MAF relays and the MAF operation is completely different. Since your car has a burn-off relay, the first thing I would do is to get a can of MAF cleaner and clean the hot wire in the MAF before resetting the ECM to see if that helps first. Then swap the POWER relay (NOT by the brake booster) with one of the relays by the brake booster (preferably the fuel pump relay). Check the voltage at the green wire at the MAF with the engine idling... Should be .4-1V.

Ray the Rat

iTrader: (1)

Thanks for the detailed info. I'll give it a shot tomorrow and let you know how it works out.

Pensfan11

I had exact same problem, it was my maf relay and sensor. You can easily and quickly tell if it is your maf by unplugging the maf. If it runs good when you unplug it then this is most likely your problem.

Ray the Rat

iTrader: (1)

Well, I had a buncha other stuff come up today, so I didn't get to it. But as soon as I do, I'll report back. Thanks, Pensfan11 for the quick check info. I think that's exactly the way mine's working....but I've got my head full of other stuff so I'll have to verify that.

Ray the Rat

iTrader: (1)

Well, I adjusted the TPS which helped the high idle a bit, swapped relays and checked fuses (since the fuel pump is working, the fuse kinda has to be good, but I checked 'em anyway) and still have the SES light. So I just ordered a MAF sensor. Maverick, I know ya recommend the GM sensor, but I'll go with a 3rd party part and if the damned thing fails again, I go with the GM part.

We'll see how things go tomorrow when I can pick the part up from the FLAPS (Friendly Local Auto Parts Store).

Ray the Rat

iTrader: (1)

The MAF sensor did the trick. Installing that along with replacing a PCV tube elbow that had deteriorated and setting the TPS voltage seem to have solved the SES light AND the high idle problem. At least for the moment. I haven't driven it a lot since I have the seats unbolted so I can install a new set of 'em, but testing in the driveway seems to indicate that all is well. Fingers are crossed.

mascarpone

where exactly is the maf relay located? i just replaced my maf sensor and i put a volt meter to the orange wire and it says its only getting 10 volts. id like to replace the relay if anyone can tell me where its located?