Okay, before someone writes in saying “Well then plug it back in”, the reason I even did this has to do with me trying to figure out why my car has a loss of power in 3rd & 4th gear under wide open throttle.

I have read here where people would disconnect the MAF to force the car into open loop, but when my car is running and I disconnect it, the engine just dies! It wont start with it disconnected ether.

I know this may be a dumb question but there must be a reason why others can disconnect it and I cant? Is this normal for the engine not to be able to run with it disconnected or could something be screwed up on my car?

Any input would be appreciated,

Matt

 

Check your MAP and TPS numbers.

 

My MAP is .49 and TPS voltage is .70 @ idle. This is from my FreeScan logs. Dose this sound bad? I know when I check the manifold vacuum with a gauge it is around 14 inches @ idle when the car is warm.

So am I to assume that the engine dying with the MAF disconnected is not normal?

Thanks for responding.

 

the car should start back up in speed density. might be because you have ported heads and a cam. since your car it tuned for MAF its possible the VE tables are too far off to actually start and run the car but even that is kinda of a stretch since the cc305 isnt THAT big and ppl run it with stock tunes.

 

So dose this sound like maybe my computer tune is off? I do have several FreeScan logs that don’t look all that bad IMO but when it comes to this computer stuff, I’m just learning. Dose anyone have suggestions on what I could start looking at?

Any input would be really appreciated. I have read through a ton of old posts and just cant find anyone having a similar problem.

Again, really appreciate the help,

Matt

 

Well, now we know your OBD I TPS sounds good, MAP I dont even remember anymore. With key ign to ON you can measure the full TPS.

How do your MAP numbers look in the log at idle, WOT?

 

My MAP at idle is .49 and WOT is .92. I am not sure if FreeScan measures in KPA, but these are the values from my most resent data log. Do these values look okay? TPS is at 4.57 @ WOT which I was told anything over 4.5 is seen as WOT by the computer.

Also, my MAF numbers are in the 370-380 range at 6100 rpm. I was told that those are decent numbers for my combination and generally cars with the same are making anywhere from 360 –380 RWH. Is there any truth to this? I highly doubt my car is anywhere near those #’s right now but who knows?

Matt

 

Well if it makes you feel any better, my car will not start either with the MAF disconnected. It's a OBD1 conversion 97 Z28. For some reason the car must use the MAF in open loop, and doesn't like to go to speed density. I would like to change my VE tables one of these days using VE master, and i believe i need to check the speed density box in tuner cat and then try to start the car.

Bill

 

Hi Bill,

If you let your car warm-up and then unplug it, will it still run?

Could it be possible that MTI programmed my computer to stay in Open Loop?
If you were to run an Open Loop program, do you need the MAF hooked up for the car to run?

I just think this is strange, is there anyone else out there that ever tried to unplug the MAF with the car running? Anyone???

 

If my car ran right now I would check it out for you. I have the exhaust off getting ceramic coated. Sorry

Bill

 

Mine wouldn't run with it unpluged either.

 

It may have to do with your bigger cam and ported heads.

You are pulling a lot more air in than the stock VE tables are set for, which would make you run very lean, which easily will stall the car.

Heck, if I tune my VE tables too low on my stock engine when in speed density, the car will stall under throttle. So, I can imagine hogged out heads and more cam duration and lift would do much more with stock VE tables!

If you can tune your PCM, try multiplying your VE tables by 1.10-1.15 or so (10-15% increase) and see if that helps. Then you can log and use VEmaster to get it closer.

 

yesterday, while the car was running, on the scanner , i unplugged and removed my MAF and replaced it w/ a descreened one. the car idled just fine during the process. I did get a MAF code that i erased after i was done. I have OBD II computer.