I've been having the fuel cut issue from the MAF sensor reading to much air. At least I think thats what it is.

Normally I run on the spring which is 7-7.5psi. Now that I have installed a custom mandel bent dual 3in exhaust and I can feel the extra power so, I'm sure I moving more air But, if I turn it up to 8psi the ECU goes into limp mode under boost at 4700 rpm. I have the emanage doing a volt clamp to hold the MAF signal to 5v.

Well I thought some thing was wrong with the volt clamp so today I logged a run and at 4760 and like 7.7 psi it went into limp mode and the MAF volt was clamped because it never went over 4.96v.

So I'm at a loss now. I contacted TechnoSquare about it and they have yet to have a local car do this. They plan on trying to make a car this in the near future but don't have any first hand info right now. I'm guessing the higher flow from the exhaust and cool air is moving enough mass to trip it. I'm just not sure why it's doing it below 5v.

I can run 8psi all day as long as its after 4800rpm.
Thanks for any ideas,
Gary

 

Strangest thing ever........must think about this one awhile.....hhhhmmmm

 

Logically it has to be linked to the one thing you changed on the car....the exhaust. Is it possible the computer has a guide value for the amount of air going into the motor and the amount of exhaust flow coming out??? Possibly the excess exhaust flow that the o2 sensors are seeing may be throwing the code.....why at just that rpm......no idea. Why not at the higher rpm's....something do do with open loop maybe???

 

Thanks for the idea but I have a 03 which has a very open ECU, plus it has a TS flash for the Greddy kit at 8psi. All the symptoms are the classic MAF limp mode with the only issue being the MAF voltage reading.

I logged the data with the emanage both the input and output MAF voltage. I think I will log the voltage straight off the MAF next to cut out any other possible errors.
Gary

 

Gary, this is a first...Greddy kit limp mode with the voltage clamped....hmmm....

Can you try clamping the MAF voltage at a slightly lower level? Maybe 4.9V or 4.8V....just in the cells below 4800rpm?

 

Do you not think it might have something to with the exhaust and a new lack of restriction???? That's the only thing you have changed..is it not??

 

I agree and was one of the reasons I contacted Techno square first. After talking to Brian it seems that the higher flows could have just brought this issue to light.

However it is not the correct operation of my current setup up. There are others running a similar or more aggressive setup with the same flash and have not experienced this issue. I feel this is something with my car (emanage/ECU). Trust me I am listening and appreciate your input.
Gary

 

GQ, I lowered the clamp to 4.95v, which results in a max voltage of 4.92v. I am very cautious about lowering the clamp too much due to the resulting lower load seen by the ECU.

When I clamped it lower it raised my WOT A/F from 10.5:1 to 11:1. So I'm not too excited about dropping it further(it only allows .05v changes)

Thanks again for the ideas
Gary

 

Quick question, Which Airflow meter is the correct selection. None of the Greddy Manuals have the Z33 in the application charts.
Thanks
Gary

 

Do you have the MAF sensor in the stock housing still? Any chance you moved it to another type of piping. This caused a limp mode issue in mine a few years ago. Also, try buying some electronics contact clener, pull the maf sensor and spray it. Could be a dirty MAF. Just some suggestions... honestly I am at a loss on this one.

 

It's still in the stock housing. Ya I checked out you and skidazzles thread "bad news of big boosters" That thread has some of the best info around in it reguarding this issue.
Gary

 

This probably won't help but I had the same problem with the procharger at around 4900 rpms. It ended up being one of the wires to the MAF sensor was frayed from rubbing against something. I got the wire soldered but it seems to not run the same.

 

Yeah, I was one of the first ones to have the major MAF issues and it was two fold for me. The first was clamping the voltage on the MAF and the second was relocating the stock MAF. I have also cleaned the MAF before. Keep us posted on the results of your find. If I think of anything else I will chime in.

 

Well I was able to surpress the boost cut by lowering the voltage clamp to 4.90v at just 4800rpms which resulted in a 4.88v This is not a solution by any means it just provided me with some more information.

I just wanted to verifiy the airflow meter selection. I currently have the NS_HW-2 meter selected in the emanage. I beleve this is the correct one. The manual calls this out for the Z32 but of course there are no charts with the Z33 in it. If someone could just verifiy this in thier car I'd appreciate it.

Thanks,
Gary