Went

So my Vette is back from the shop running quite nicely and my pocket book is $480 lighter. Aklim, you were right I shouldn't trust my nose. Instead of a lean burn it was very rich (although I and a friend didn't smell unburnt fuel). I have a really bad sense of smell. And PatternDayTrader, it was not the fuel pump relay. What it turned out to be was the MAF. What I'm confused about is being it was a bad MAF, shouldn't the car thrown a code for that? The mechanic checked for codes right off and found nothing. So had I. He put on a new cap/rotor too. The old ones were not terrible when checked but I said go ahead.
Anyway, it runs nice and strong once again.

Went

PatternDayTrader

So I'm not surprised the MAF did not set a code. The reason being is the MAF is an input signal to the ECM. The ECM has no way to know when an input signal is screwed up. Lets say the MAF is signaling there is twice the amount of air going into the engine than what is actually going in. Well the ECM has no way to know it is being lied to, so it adjusts the fuel mixture according to what it thinks is happening and then the car runs poorly. In the event it gets no signal at all then it will set the code.

Went

So what's new now? A code 36 set today. I see it's the MAF burn off relay error. Poking around I found a tiny broken vacuum line and fixed that. Disconnected the neg. battery cable to reset things. Will see if it comes back tomorrow. Maybe need to replace the two MAF relays??

Went

aklim

https://www.corvetteforum.com/forums...ay-issues.html

I don't think you are on the right track. Code 36 is the burn off relay so I'm not sure what it has to do with the vacuum line. What does it go from and to?

Went

The vacuum line was just a lucky find and repaired. I wasn't thinking there was a correlation with the code 36. I just pulled the neg. cable to reset stuff and see if code 36 comes back. The MAF relays have not been changed since I purchased the car. The new MAF sensor the shop put on is a Bosch unit. Here is a photo of the elbow (center of photo) vacuum fitting. The vacuum line is attached to the bottom.

Went

Went

So I had a new MAF put on and within a couple days had a code 36 set. So I replaced both the MAF relays. All seemed well then a code 33 was set and it ran terrible. Took it back to the shop and they installed another new MAF (Bosch/Echlin brand) and it runs great once again. I wonder why one MAF will not work and another will? This is something I've read in the forum many times. People will go through two or three before one works correctly. Is this just an issue of poor quality manufacturing or deviation in specification of an electronic component in the MAF? Could capacitors, resistors and the like be to the high or low side of their tolerance range and cause a signal to fall outside the settings in the ECM? Just curious what the root of the problem might be.

Went

aklim

Maybe it is made by Bosch FOR Echlin? IDK but larger companies sometimes "private label" stuff. Just because we are blood brothers and have the same biological parents does NOT mean that we are the same person.

Went

Believe so, Bosch made for Echlin. I agree with the above. But having worked in manufacturing and process control for many years it just made me wonder what causes such a high failure rate on the same new parts within a brand name. What factors might be at play. Just curious...

Went

aklim

I sell products that we have made by the same company but under my brand. Some are 50%, some are 60% and some are 80% active ingredient. I have no doubt that if the factory that made it for me had to choose, they'd satisfy their bigger customers first. That said, they might not know or they might, hard to say. The product they make for me to private label might not be the best from time to time. If they don't know, that is one case. If they do, I suspect they would give the better product to their best customer, whomever it might be.

Signed
The Cynic