mvftw

iTrader: (1)

I have a '86 Camaro, 2.8L/Auto. It runs great when it's still cold, but when it warms up it runs like a dog. I'm Not getting a code lite, the lite does work. I put it on a snap-on scan tool, nothing came up that was out of spec. What would cause it to go into open or closed loop mode and Not trip a code. Maybe a weak MAF?

Joe_L

Sounds like MAF. Odd that a snap-on scan tool would not bring that up though. Maybe ECM is done.

I would say get an MAF off another car that you knows works and test it out. Or buy one on the bases of you can return it. Give it a try.

When my MAF went my car ran perfect cold. But once she heated up, it would quit while driving. Hesitate etc.

TomP

Joe, my mechanic told me that MAF's can go bad and not even register on a scan tool. He told me once of a 2.8 Camaro he worked on, which was having trouble. He put his tool on the car, and it didn't show up anything as bad. He started pulling items to replace them with good stuff- and he noticed the MAF board was melted! Go figure. The car wasn't even throwing a code.

Oh- yeah- if the orange MAF frequency film (we don't use a hot-wire Bosch MAF like the V8 TPI guys have) is bent/kinked/warped/etc, it's time for a new MAF.

TomP

Oh, hey, that's interesting that your (Joe's) bad MAF threw the computer out of closed loop! It's not supposed to affect open/closed loop operation! Here's what's supposed to:

- Engine run time must be for a few minutes
- coolant temp must be above 77 degrees fahrenheit
- computer must sense a changing value from the oxygen sensor

When an oxy sensor's cold (because of a cold exhaust), it gives off one constant reading. As soon as the computer sees that the oxy sensor reading starts to fluctuate, it drops the car into closed loop mode. See if you can switch that scan tool to read the CTS, and examine your oxy sensor wire to see if it's melted on the exhaust. You might even want to replace it if it's the original.

As far as I've read, the computer will always read the MAF. The only time it'll ignore the MAF (and use a "default" value) is if the MAF throws an error code. Feel free to correct me if I'm wrong on this part, but I thought the MAF was always used?

Joe_L

Yeah another thing too.
Since the replacement.
It did this same thing again.
WEll I had a bad leak of oil spraying out. The blow by was really dirtyingthings up.
Well teh SES light came on, and I reset Battery. Then it came back good old MAF.
WEll I pulled the bugger out. I had oil on the inside of it somehow. Cleaned it up. Put if back in and never had trouble with it again. Odd I know.

1991tealRSt-topGuy

what was the frequency of the MAF?

mvftw

iTrader: (1)

The first thing I did was a complete tune-up, adjusted the timing to 12-13, & replaced the O2 sensor. I did not see what the output was of the MAF. I was told I can pickup a MAF for $80 wholesale. It maybe the way to go. It's funny how the car runs great when it's cold.

89camaroRSV6

ok simple ... do u have a laptop... if u do i posted something

https://www.thirdgen.org/techbb2/sho...threadid=83003

check that link out and build the ALDL connector for like 5 bucks and even if u dont have a laptop get a buddies laptop

that displays all the sensor info just like a scantool...

but if u run the car for sometime with the laptop running that WInaldl software...

that usually shows overall asto whats going wrong...

i detected my TPS problems with that stuff...cos sometimes some sensors work fine until it gets hot...

that software detects faults too in the ECM (its basically a free scantool with a lot more functions can be montiored at one time)

mvftw

iTrader: (1)

Just want to make sure about this. I checked my MAF orange film and it was warped, I got another one that the condition was Not known, I know it was tossed around, it also has a warped film. Both did the same thing, after warm up it ran like #$%%. I went to the parts store and looked at a reman MAF and it had a warped film. What gives...I hate to spend $80 if warping is normal.

86bird_28v6_5spd_ramair

you sure your temp gague is working right and your not over heating the car??? even though the gague goes up to 260 before it gets red, anything past 220 will make it run real slugish.

thermo should open at 195 but then normal temp should be around 160-180.

mine runs about 165 all the time ,once warmed up and thermo is open.

mvftw

iTrader: (1)

My Temp. is on the money, I checked with the scan tool. The fan also comes on when it should. I think it's the MAF or Computer.
Some said to tap the MAF, if the RPM's change, it's bad, also tap the Computer. I would like to hear back on the MAF's orange film. Is warping Ok?

86bird_28v6_5spd_ramair

If you even think it could be a 25% chance its a bad MAF just change it. they do not cost that much and its kinda like plugs, doesnt hurt to change it early before it need it.

but remember to unhook your batt, never unplug or plug in a MAF with the batt hooked up, it can fry it. least what the auto store told me.