Intermittent check engine light. Maf? Need help.
 

Hi guys I have an 88 firebird formula with the 305 tpi and have been having an issue with the check engine light. It is not there when I first start it in the morning but comes on after I restart it. Powerloss and rough idle when it is on. Could it be an maf relay problem? I took it to a shop and they said it was an maf issue but they couldn't fix it.

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

I forget, I think it was 36 or 32
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Re: Intermittent check engine light. Maf? Need help.
 

32 or 36, I forget.

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Ok, thanks. I'll do some voltage tests on the wires and check the ECM as well. Maybe cleaning the EGR would fix it?

Re: Intermittent check engine light. Maf? Need help.
 

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Re: Intermittent check engine light. Maf? Need help.
 

Awesome, thanks for the help!

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

A MAF burnoff relay code wouldn't cause driveability issues. But you may want to check the MAF power and burnoff relays. The burnoff function itself is unnecessary and it doesn't matter if it doesn't function. I can be programmed out with a custom PROM chip.

GD

Re: Intermittent check engine light. Maf? Need help.
 

I just checked the codes and it says 33 and 34. Is that related to exhaust/ O2 sensors or intake? Car burns really rich.

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Any specific tools I would need for these tests? I'm basically clueless in regards to electronics.

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Driving down the highway today with no engine light (intermittent) and suddenly I had a complete loss of power, no throttle response at all. After about a second or two of zero power the car went back to normal, but the engine light lit up just after that, while I was driving. Does this give any hints as to what my 33 and 34 might be?

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

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https://cimg0.ibsrv.net/gimg/www.thi...f1ec79b70.jpeg

Re: Intermittent check engine light. Maf? Need help.
 

How to I get ahold of a fused jumper? Can I make one?

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

After connecting the junper to ALDL G could I connect the other end to the fuse labed BAT and use that as my 12v source?

Re: Intermittent check engine light. Maf? Need help.
 

Re: Intermittent check engine light. Maf? Need help.
 

Still in the process of diagnosing my codes. Could a bad Catilytic converter be code 33? There is a knock/ crunchy sound in my converter when idling.

Re: Intermittent check engine light. Maf? Need help.
 

The computer is entirely unaware of the converter. It doesn't care if it's there or not. So it is not related to your codes.

I recently moved to the EBL system and eliminated the MAF from my equation. This has the benefit of not needing any of those circuits, and also never having to worry about replacing a bad MAF or it being a flow restriction to future upgrades.

GD

Re: Intermittent check engine light. Maf? Need help.
 

While true if the cat is falling apart and internally clogging the restricted air flow would lead to rich running and random sudden power losses. This would be an actual issue vs just bad sensors tripping codes.

Re: Intermittent check engine light. Maf? Need help.
 

Ok, that makes sense. Is there any way to change that thing or would I just have to buy a brand new one? Maybe I can get a nice one from a wrecker?

Re: Intermittent check engine light. Maf? Need help.
 

I would run through the wiring as all those test cost is time. You can use a touch less/laser thermometer to see if the cat is clogged up. Just google how to do that I'm sure there are videos etc that show how.

It could be a clogged cat, how rusted are the bolts can you simply un bolt it and test drive it and see? Or is it rusted solid and would need to be cut off? If you have the means I would drop it off and stick a temporary pipe in its place... temporary being defined at how enforced having the cat is where you live :)

Also the knock are you sure its the cat or could it be an exhaust valve?

Re: Intermittent check engine light. Maf? Need help.
 

If it turns out to be the cat buy a new one, since there is no aft o2 sensors on these cars I would buy a high flow cat to stay legal and somewhat environmentally friendly. Most wrecking yards will not sell you the cat, they have platinum inside them and are worth more as scrap than they can sell them as used parts... and I think some states have laws about used cats being sold. Depending on where you live you can probably get away with no cat but if the car is ever inspected they can ticket you under the federal laws requiring the emissions not be modified... though NY, CA, and a few other states are the only ones that really hassle you on a car this old.

Re: Intermittent check engine light. Maf? Need help.
 

I live in California so that wouldnt be an option for more than a year or two. It looks like all the exhaust before the cat is rusted and all the exhaust after it is still nice and shiny. I could probably get it off with an impact. I'll try that and see if it helps any. Also, I want to check my vacuum lines in the engine, what tools would I need for that?

Re: Intermittent check engine light. Maf? Need help.
 

It's not the valve, coming from near the cat, not by the engine.

Re: Intermittent check engine light. Maf? Need help.
 

Since you are in CA you will have to buy a CARB certified cat which cost alot more. Does it pass the sniff test?

Re: Intermittent check engine light. Maf? Need help.
 

Well the exhaust smells super rich of thats what you mean by sniff test. My current cat did pass smog last year, maybe I put that on when I need to smog it but use a non certified cat for normal driving.

Re: Intermittent check engine light. Maf? Need help.
 

No the inspection where they put the probe in the exhaust pipe, that is commonly called the sniff test around here. Also CA has that 1000 dollar fine for exhaust too loud that started this year -- so yea be careful, they are no longer doing the fix it tickets.

Re: Intermittent check engine light. Maf? Need help.
 

Ok, I'll pull the cat off later today and post results, thanks for all of your help!

Re: Intermittent check engine light. Maf? Need help.
 

You can do a pressure test using the O2 sensor port to check for a plugged cat. Should see no more than 1-3 psi back pressure.

But even if the cat was plugged - this wouldn't throw a MAF HIGH grams/sec code. Since the car only has a single cat, it being clogged or not affects airflow through the entire engine - which would lead to the engine choking and the flow rate through the MAF would be low, if anything.

It sounds like you probably have multiple problems. Definitely check out the cat situation but don't expect it to fix that code.

GD

Re: Intermittent check engine light. Maf? Need help.
 

This is why so many people are moving up here to Oregon. We used to have such a nice quiet state.....

GD

Re: Intermittent check engine light. Maf? Need help.
 

Yeah I'm tempted to just pay a shop a ton of money to fix it all so I don't have to deal with it all. It only has 52,000 miles but the amount of Gremlins makes me think it wasn't kept well. Maybe I'll just rewire the maf, change the ECM, buy a cat, and check the hoses.

Re: Intermittent check engine light. Maf? Need help.
 

Took a look at the Cat today, couldn't get it off because of rust, so Im going to go be some rust remover. In the process of trying to get the Cat off, I found that the clamp that clamps the exhaust to the Cat is loose, and that the fit between the two pieces is letting air get out. I'm going to buy a new clamp because that one is way to rusted to work and see if that fixes rattling/exhaust leak problems. I've also been noticing stuttering at 3500-4500 rpm and think that maybe my intake is whack. I have the original air filter box with a k&n filter in it. When I took a look at it, it was just a single black dot 3 inches in diameter where it was taking in air. I'm thinking that isn't normal. Before I bought it it had a cold air intake but California smog wouldnt even pass that. Finally, it is now taking a couple of starts and plenty of pumping the gas to get this thing fired up, could that be injectors? If any of you guys have any advice or have found solutions to these problems please let me know! Thanks for all of your help thus far guys.

Re: Intermittent check engine light. Maf? Need help.
 

Yes - for an 88, if it has original injectors they would be extremely suspect. They are notorious for failing - especially when hot.

GD

Re: Intermittent check engine light. Maf? Need help.
 

Ok, I'll check those.

Re: Intermittent check engine light. Maf? Need help.
 

Check all your vacuum lines too- particularly the EGR valve line- one of those comes loose and you'll throw a code...

Re: Intermittent check engine light. Maf? Need help.
 

Do any of you guys have experience with making and using fused jumpers? Tuned Performance said just some spade connectors and a 5 amp fuse. Would I have to get a fuse holder then extend the wires, connecting one to the battery and one to the ALDL/ OBD1 port G? I am just making sure I don't mess up and fry everything.

Re: Intermittent check engine light. Maf? Need help.
 

Turns out my Cat is busted, pulled it off and a bunch of little pieces of honeycomb came out. Buying a new one from Magnaflow. Thanks for all the help that got me this far!

Re: Intermittent check engine light. Maf? Need help.
 

Final post- the cat was bad, when I replaced it the car has more power than ever and the engine light is off.