prowlingleather

Back again (it's always something with my DD...).

I've had some issues with fuel pressure since I dropped in the new pump/sender back when I first got the car; finally just went ahead and dropped a new assembly in there (another Delphi because that's all Summit had, and I was doing this on extremely short notice) since I didn't have any pressure at the rails after shutting the car off. I think it ended up being the check valve because I finally got everything working great; fuel trims hovered around 0 as they were supposed to, car accelerated and drove better than ever.

Few days ago, she started choking horribly and refused to accelerate; at a few lights/stops, she completely shut off. Fuel trims showed around -20 to -30 (an obvious red flag) all the while, and you can smell and feel she's not running right. She holds pressure, however, and starts right up.

I have a new MAF, just did the intake manifold gaskets (no vacuum leaks that I know of; I chased and fixed one earlier so I'm pretty confident in that), new sender/fuel pump, fuel filter swapped out about two or three months ago, new air filter; I don't think it's anything with the fuel or air systems (but I could be wrong), though she's behaving like it.

I'm honestly kind of lost here; maybe something with coils/plugs? I'm not sure how to test them, though, and I'm outta money to drop her off at a shop until Delphi refunds me for the old sender/pump. Any ideas would be highly appreciated; I can go run scans as needed. Thanks, guys!

fst100

iTrader: (5)

if its choking and the fuel trims are in the negatives, my initial thought is leaking injector. have you pulled the plugs and checked if any of them are wet?

prowlingleather

Haven't pulled plugs yet; I do most of the work on the car about 200 mi from where I'm currently at so, besides the actual plug socket, I don't have anything to really pull them with. To check injectors for leaks, could I just pull them out with the rail and see if they leak when the pump primes?

Since the first day it happened, she's been cooperative; I drove about 40 miles to take care of errands and just to see if she'd show the same symptoms. Fuel trims have been alternating as normal, no choking, no stalling at idle, hasn't thrown a code. Whatever it is, it looks like it's intermittent.

prowlingleather

Speak of the devil. She threw a code, finally. P0102 (low MAF circuit voltage); considering the MAF is new, the air filter is new (and looked clean as of a week or two ago), the intake gaskets are new, and the intake vacuum hose and PCV were just checked for leaks/fixed, I'm thinking it's something electrical.

Something with the wiring harness, maybe? Damn.

bammax

You said the maf is new, but you didn't say what maf or who it's from. Much like any other sensor there are some brands that don't play well with the ecm.

prowlingleather

My bad; the one I have in is a Walker. I also have a Cardone one (miscommunication with the shop that had it ordered in for me) lying around if the ECM prefers that.

At the time I replaced it, I didn't have much to choose from in terms of brands since I was strapped for time; I assume the original would have been an AC Delco?

bammax

The original would have been an ac delco or delphi in the all aluminum housing. They don't make it any more. Now it's the plastic version with the wire adapter or a rebuilt original. I've heard that the newer plastic version may need to be tuned, but I don't run one so it's only hearsay. The rebuilt original should be plug and play, but you never know when it comes to part store rebuilds.

I'd swap on the spare then reset the codes and see what happens. Make sure to check the wiring in the connector because they can come loose from the plastic case and back out. Worst case is that the problem stays the same and you wasted a half hour swapping them.

prowlingleather

Swapped and took her for a drive; no code yet (it's been about 40 mi), but I'm a little suspicious of how she's running just based on sound and feel. Fingers crossed.

I also dug out a multimeter, and it seems that the actual harness is delivering power fine and has a functioning ground, so I guess it's sensor side. Can anything other than a MAF give a P0102?

Thanks everyone.