I am using TunerPro RT on my laptop for my 86. It shows the MAF flow in g/sec. I haven't used any other software for scanning, so my knowledge is limited. Try posting in Scan and Tune section. It might take awhile to get info, but there are guys that are steeped in info.

 

Why not just download TunerPro RT, they would like a $30. contribution, but when did it their paypal wasn't working...I use it and think it's a good product. BTW, you may have to download a free USB host port...you can get that free from Moates.

 

OK, here's the latest.

I downloaded TunerProRT and bought a Belkin serial adapter, but haven't been able to get a connection... I'll work on that later.

Today, I decided to try diagnosis again. The SES light has been on all day and I thought I might have better luck if I try diagnosing it while the engine was hot. No such luck. After clearing the codes and running the tests listed in the factory manual, neither the code 33 or code 36 set--damn intermittent problems!

Just for grins (and I needed some at this point), I followed the instructions for intermittent problems... I jumpered the G terminal to 12V, which powers up the fuel pump and the MAF. I had to take the connector off the MAF to get any voltage reading, and the MAF signal read at about 21mv. The manual said it should be low voltage (less than 250mv, but that's a LOT less) or low gm/sec flow on a scan tool (of course, I can't see anything on the scan software because I can't connect the ALDL connector because the jumper is in the way!).

Anyway, the bottom line is that I can't get past "intermittent" as a conclusion during diagnosis. After going on weeks of dealing with this problem... I'm tempted to just start throwing parts at it. MAF first, ECM second. If I take it to a shop, they're likely to encounter the same thing I am... no codes are being set during diagnosis... leaving them to their "best guess", I expect.

Any other thoughts, ides, suggestions, brilliant diagnostic tricks?

 

While following the trouble shooting on 33 did you wiggle the wires while testing? that is part of the test. Also, if you have read 36 it states "A faulty MAF sensor should not be considered as the cause if Code 36 is set."

I really suspect you have a bad wire or bad connection in the ciruit.
When you applied 12 volts to terminal G...was the fuel pump running?
it should run constantly..if not then the problems in the FP circuit.

We live close..if you need help, my scanner is just sitting.

 

Somebody told me or I read that the power and burnoff relays should be changed every couple of years. I just did it and my codes went away

 

Thanks, Rick (PM sent).

Yes, I wiggled what wires I could during code 33 testing. In interpreting the comment on code 36, I found myself wondering if that only applies if ONLY code 36 is set? If both 33 and 36, does that still apply? I wish I knew...

If it's a bad wire, I'd love to find it... but we all know how much fun that can be

It is good to hear what worked for others... at least I maintain some faith that I might eventually figure out what is actually causing this. The good news is that the car is still driveable (except when it suddenly dies, occasionally, while at a stop light).

 

There's really nothing mentioned in code 33 trouble shooting about replacing the MAF, that said, I know a few guys only got rid of them (33 & 36 )by doing so, Rich Silvestri is one, he bought a Bosch I think for less than $200.

I'm definetly not suggesting you do this. I would check the connections at the ECM first, then the fuel pump circuit along with trouble shooting the other MAF circuits for an open, that's a PIA. Good luck.

 

The other day I called the Corvette mechanic and double-checked that he would be in the same boat as I was trying to diagnose an intermittent problem (that is, it would be a waste of time and money to have him check it out if it wouldn't set a code during diagnosis). He agreed and said in his experience it's either the relays or the MAF. Since I've already swapped out the relays, he said the MAF would be his next move if it were in the shop (when it comes down to diagnosis time dollars vs. parts dollars).

If I can just find enough time to pick one up at a parts store... I just might replace it.

 

I was planning to do more diagnosis this weekend, but came down with a nasty cold that zapped all my energy. I decided to just get a new MAF and hope that solves the code 33&36 problem. I replaced it yesterday and so far, so good, although I've made only one short trip with the car. I'm keeping my finger's crossed.

I made a few calls before finding one in stock: Schuck's had the Bosch reman for $170, Autozone seemed to have the same part for $220. Just for comparison, I called the local Chevy dealer: $650! Yikes!

 

And the winner was....$170?

 

Yep, Shuck's for $170... I'm a frugal (OK, "cheap") bastard... can't see paying more for what seemed to be the same part by the same remanufacturer.

After two 45-minute drives today, still no Engine light--I just might be able to uncross my fingers soon... it's tough keeping them crossed for such a long time Still, I'll probably give it a few more days before I feel comfortable concluding the problem is fixed.

 

Both relays on an 87 are interchangable, try switching the relays and see what error codes you get.... also, just fixed an 87 problem with the same codes by replacing both relays $22.00 total @ NAPA
Just a thought

 

[QUOTE=rick lambert]There's really nothing mentioned in code 33 trouble shooting about replacing the MAF, that said, I know a few guys only got rid of them (33 & 36 )by doing so, Rich Silvestri is one, he bought a Bosch I think for less than $200.

QUOTE]

I bought a Sorenson rebuild of a Bosch (after lengthy sessions with the FSM and the DVM stalking a Code 33). It died in a couple of weeks (Code 34, I think), and the only replacement AZ had in stock was a Wells. They were willing to take the first one as a swap, and I have been running on the Wells for the past several months. (The Wells looks just like a MicroTech.) I am no advocate for using aftermarket "whomadeit?" stuff, but by that point I just wanted to enjoy my car again.

 

I hear ya, there! I'm willing to put in a fair amount of effort to try and diagnose the true problem, but the law of diminishing returns kicks in fairly quickly. I enjoy working on the car and solving the problems as long as I'm making progress (with minor setbacks, of course), but after endless hours of frustration and repeated dead-ends , I just want it fixed!

I'm counting my lucky stars, right now... I haven't seen the engine light come on for a solid week... I'm thinking the MAF was the problem. Hopefully, my experience helps someone else faced with the same kind of intermittent problem... my favorite kind... they drive me

 

intermittents can drive the best to the edge, even following the TS trees. Most of the times it's as simple as a connection or something temporarily sticking. Glad it seems to have cured your problem, have to admit, theres been times when I said screw it and bit the bullit.

 

K87ZZ4, thanks for taking the time to write this up. I find it very helpful when folks detail their entire experience - it really helps the rest of us


Gary

 

I have the same problem in my 87
except mine is always on now
at first it was like yours
now it runs super rich

I checked all the wires for power
did the service manual checks
all came out ok

then i changed the MAF and the relays
still did not fix it

I am now using a Snap On Solus diags unit
When i shut down and turn the key on it doesn't show that the burn off is activating.
but if I check the relays it is

So I am leaning towards the ECM is not sensing it or something like that

I also had a problem with my fan not working and the stock ECM chip
When I changed it to an aftermarket hypertech the fan works

Replacing the relays and MAF didn't work for me.
still stumped.

I let you know if it is the ECM
Tryng to find a way to test it

 

You're welcome, Gary... and thanks for saying so. I find a lot of value in other people's experiences; sometimes, it's almost like you've done it once already before tackling the job--and we ALL know how much quicker a job goes the second time you do it!


Best of luck on your situation, JETSET... I feel your pain but wish you some good luck!