Stock ECU without MAF

[Number996]

Hey guys!

I'm having some trouble here. Let it be said everything electrical like IPS etc has been double checked...

My newly rebuilt galant came with an HKS VOC before the rebuild. I since purchased a 2g MAF with coversion to 1g harness. While idling she will throw a fit and jump in RPMs from 1k to 2-3k and hold. When she does this, she bogs out and wants to stall out if i open the throttle (leavin me momentarily stranded somewhere in the neighborhood). After she stop having a fit the RPMs will drop back to 1k and she responds to throttle.

I have checked EVERYTHING.

So i unplugged the 2g MAF and reinstalled the HKS VPC (this is what the car had when i bought her, hence no stock 1g MAF)

She ran worse, cutting out at 4k RPMS.

I redeleted the VPC and now she has no MAF and no VPC and runs alot better minus bucking at low RPMs.

The base timing has been set.

Should i continue to drive her without the 2g MAF untill i can afford link and spreed density harness?!

She runs so much better without a MAF. I've found threads that say both do it and don't do it. It seems some cars run without, while other fall in their face when there isn't a MAF.

Thanks for your input guys

 

[Defiant]

Do not run the car without a MAF.

The MAF tells the ECU how much fuel to add.

 

[James]

Don't run your car without a MAF. That's just stupid.

Diagnose and fix the real problem.

 

[Number996]

I just plugged the 2g MAF back it. She bucks all over the place and the VPC just makes it worse

 

[James]

Then diagnose the problem man.

Check the TPS, check the ISC, have you blocked off the FIAV? Have you tried a know working 2gMAF? Have you checked the ECU? Any vac/boost leaks? No CEL?

 

[James]

Check and test the plugs/wires. Check/clean the injectors.

 

[turbowop]

Are you using anything to compensate for the 2gMaf? SAFC? DSMchip? Is the MAF signal wire still intact? Installation of a VPC probably requires it to be cut and installed to the unit.

You can't just install a non-stock maf and expect it to work. Even worse is completely removing it? /ubbthreads/images/graemlins/uhh.gif

 

[Jason G.]

I'm just speculating but it sounds like you have a car where the previous owner installed dated electronics (like the VPC)and more than likely hacked the hell out of the wiring harness.

Give us a run down of what mods have been done to the car.

 

[Xcelerate]

There might be a wiring issue here. If the VPc is hardwared then make sure you rewire the ait wire back to the stock maf sensor. Make sure the stock maf has all the honey comb too otherwise it will be a problem without custom tuning.

 

This happened to a friend of mines 91 Talon TSI AWD awhile back....its an ecu malfunction,well atleast his was..At very low rpms it slightly acts up but driving and boosting its normal..Even won some street races like that,lol..But its definietly not safe to do so check your ECU..

 

[Number996]

Diagnose the problem and fix it? Wow. Next time just don't comment.

Everything has been tripple checked and is working. The problem lies in the MAF.

She drove fine without a MAF but sometimes would throw a fit and die whenever throttle was applied then after 5 minutes would go back to normal, however:

Went back to VPC again (and let me clarify t's the VPC plug and play harness no hackin up wires and wire harness has been tripple checked and is fine from what i can see nobody has hacked it up for a safc etc) and like before she ran worse with what i believe is fuel cut problems all over the rpm range. I DO NOT have a wide band, ive spent all my money already and am poor for the next 2 weeks.

She seemed to run best on VPC with idle, gain, and response turned all the way down (counter clockwise)

Even with knobs turned all the way down she's still runnig stupid rich

When i unplugged vpc she wouldn't even drive without a MAF like before. She just dies after you touch the gas (and from homework i think this is how its supposed to be without a MAF)

So i plugged the 2g MAF in again. She runs better and better every time i try this but now she dies when i'm moving and release the throttle.

And an imterestig development, now when the 2g MAF IS plugged in, i have no check engine light (goes on when key is turned to on position then off after 5-6 seconds and doesn't come back on)

I know that the simple solution is to go eprom/link/speed density but i am out of mony for now and need the car drivable.

Any input is appreciated except for comments like diagnose the problem and fix it. duh.

Thanks guys. Couldnt have made it this far without yall

 

[496of2000]

I thought the VPC was designed for the 1g MAF and 550cc injectors. Is your ECU chipped for 2g mas?

 

[turbowop]

The VPC is designed to allow the car to run in speed density. It's not for use with any Maf. The VPC also has chips that can be changed out depending on the injector size used, though that was very limited. I think the largest injector that could be used was a Denso 720cc and Buschur made a custom chip for that, but it was pretty much only for racing. The VPC is old technology and not nearly as good as what you can get now for tuning.

None of my questions have been answered yet...

 

[496of2000]

Just searched, my badd... I'm wrong. I forgot.

 

[Number996]

Sorry, turbowop - and you're absolutely right

The car was purhased with a vpc. The ecu that came with ran, but was fried from leaky capacitors. It was socketed and epromed and car had stock 450cc injectors, hence why no MAF. The ecu must have been what was compensating for the VPC.

I purchased and am using a non socketed oem galant ecu. So no, i was not compensating for the 2g maf. No afc. This weekend i'm buying and installing evo8 injectors and an apexi safc with a harness. This should fix the unmetered air issues.

 

[Number996]

And MAF signal is in tact from what i can tell. No logger. But there is no CEL when the 2g MAF is plugged in

 

[turbowop]

The VPC is what allowed your car to run mafless before. Installation of Evo injectors and SAFCS should fix you right up, that is, if you can tune it. But those Evo injectors will get you way closer.

 

[Hondasi88]

When i came over and you starting talking about "VPC" I was stuck for a minute...But like turbowop said u shouldn't have a problem we will have identical setups.

But ima tell u re-wire that fuel pump! I was surprised how higher gauge wire treated me.

 

[Number996]

The guy said he already sold evo8 injectors. So he's hooking me up with a set of rc550's. Hope they and the safc do the trick!