Uriel

Hi all, I just got my '86 a couple of weeks ago and have ran into my first problem.

The other day I started the car and it started in a cloud of smoke and was running very rough, idle low and struggling and the SES light was on. I was at work so needed to get it home so drove with the light on, even though I normally wouldn't. Drove to a gas station, the car was warmed up by the time I got there, switched off and when I came out and started it, it started perfect, idle was fine and no SES light. Drove home without any problems. The next day, started badly again and the SES light is back on. Pulled the codes and had 33, 34 and 36.

Searched the codes and figured I have MAF issues. Cleared the codes and started it up. Struggles to start and the idle is rough and it's trying to stall. SES light comes on instantly. Checked codes again and just have 33.

Disconnected the MAF and it makes no difference whatsoever.

Found this site with diagnostic flow charts for the various error codes: http://members.shaw.ca/corvette86/

I followed the chart and test 3 (MAF terminal E to ground) gave 9.4 volts. It says use a test light, but I only had a multimeter. I'm assuming the 9.4 volts is ok and would count as 'test light on'.

Test 4 (MAF terminal D to ground) according to the sheet should read 0, but I got 1 volt.

Test 5 was fine - 5.03 volts.

Going by this, my problem should be a faulty MAF. But, I'm not sure that the 1 volt reading for test 2 should count as 'ok' or 'not ok'. Following 'not ok' and disconnecting the burn-off relay the test still gave 1 volt. Which according to that document is a short from the burn-off relay to the MAF sensor.

The question is, is that 1 volt to the MAF from the burn-off circuit (terminal D) causing a problem? Or do I need a new MAF?

Fork501

I was getting a code 33 on my MAF on the '88 about a year ago. I replaced both relays TWICE and still got it. After about a month of moaning and groaning, I bought 3 new MAFs before I got it fixed.

My advice is to replace both relays and see if it fixes the problem (it's cheaper to throw $30 at the problem than $300+).

After you replace them, disconnect the battery; I'd recommend 30 mins. 30 mins seems like a long time, but you KNOW that your OBD has reset itself in 30 mins. If you still get the code, replace the MAF.

Now, if you have to replace the MAF, DO NOT buy one from Advance Auto Parts / Bennet / Pepboys or any other chain autoparts store, because they try to give you them made from another company. Either buy it from GM, or if you MUST buy from them, demand it be a Bosch.

This is one of those parts, where you will quickly discover that cheaper is NEVER better.



Sorry, I know that wasn't EXACTLY your question, but there is theory behind the maddness:

Let's say that the 1 volt turns out to be from your MAF. You will have to replace both relays anyways if you buy a new MAF; you can't use the same relays again, because they may have caused the short in the first place

If your MAF has never been replaced, you will need a new one very soon, either way.

Best of luck!

~Derek

RRT vette

Do the test for the code 34 and 36 also. Depends on what you get as to what to do. Not sure about that 1v you got.

DVS 99

I also have a 88 and fought code 33 for more than a year. Replaced ECM(twice) along with many new MAFS (including new relays). Finally found the problem. It was a misadjusted TPS sensor. Felt very stupid but relieved to fix it. But if anyone has a code 33 I would recommend checking TPS signal voltage at idle and compare to spec.

vinnies87

You don't need to wait 30 minutes for a reset after you disconnect the neg cable, 10 minutes works just fine...