breathment

ok. so today was the worste day my car has had yet.... im just going to list the problem i have, and then go into detail..

#1. super crappy idle when cold. (when reved to 3k and held, engine will fluctuate from 3k to 500 rpms... also will sometime stall when u press the gas in idle)

#2. hunting idle once warmed up. (fluctuates about 300 rpms when idleing. or when holding at most rpms.)

#3 slight loss of power around 2000 - 2500 rpms. (engine feels like its missing of kinda slowes when accelerating around 2000-2500 rpms.. i have seen this problem quite a bit here on the boards but with no answer... common problems with TPI?)

#4 super lean. BLM's are constant at 160 both idling and at different rpms. both accelerating and cruising..

#5 lopy idle some of the time. some times the engine will idle just perfect, with the exception of the hunting idle. but today i had it started. and the idle would drop down to like 300 and go up to about 700 and just keep going back and forth, almost stalling and then revving up a little.. engine would shake like it was about to stall, and then rev back up. also...

#6 while i am having the lopy idle (problem #5). the vacuum of the engine will go from about 18 inches. down to about 14 inches. and will kinda follow the engine's idle. however even if u rev the engiine to about 1000-1500, the vacuum will still fluctuate some, but the engine rpm will be a little more steady.. HOWEVER.... and this is the stumper.. sometimes it will have the lopy idle with the weird vacuum. and then all of a sudden the engine will idle perfect, and the vacuum will jump up to a VERY steady 18 inches...

#7 backfire through intake.. when the engine was idling rough. i tried to rev it up some by opening the throttle to about 1\8 open. and the engine stumbled really bad and slowly the rpms went up, but all of a sudden i hear kinda what sounded like a quiet bang, kinda like hitting the plenum with a screw driver or something hard. and i felt it on the throttle blades, and then it did it again, and at the time i didn't now what it was. but i figured out it was a backfire... so i turned off the car.. started it about 5 min later, and it happened again.

#8 code 44 (O2 indicating lean condition.) today when the engine was idling very roughly,the check engine light came on and gave me a code 44. (first time ever that i have gotten a code 44....) turned the car off, and when i turned it back on, the light was off...

Now i have checked the timing, and it is right at 6*.. however i find it strange that in the past i have checked the timming. and it was at around 18* advanced. but now it shows 6*.. i have checked it twice and it shows 6*.. so maybe i was reading it wrong before. or maybe the balancer slipped. but when i disconected the EST wire. the engine ran even more rough..
Plugs and wire are checked and are less then 6 months new.. compression was tested on the drivers side (will be checked on passenger side once i can remove all the crap over there.) and was around 180 for each cylinder.. fuel filter is new, fuel pressure is at about 42 psi. but the needle on the guage moves back and forth about .5 psi and u can also feel like a slick ticking when the guage is in ur hand, that corresponds with the needle movement. but i guess it might be because of batch fire..

this is all i can think of for now.. please give me all ur ideas, and check back here often!!

thanks!!:hail:

mrr23

is that 42 psi with the vacuum line off? if so, then your pump is on the way out.

flotsamm

Hows the IAC and passages? What other info sensors have you checked out? I had a similar problem recently, and I ended up chasing my tail trying to figure out the problem. I replaced the CTS, 02, IAC, MAP, fuel filter, TPS, ICM. I did the tap test on top of the ECM also. So far so good, but I dont have alot of faith just yet. I dont know either what sensor was the problem, but they were all 12 years old and needed replacing anyways. Another thing that may or may not be related is the AC compressor. When my heater or AC is turned on my idle will lope like you described. This is from being not charged up on freon.

It could as simple as a stuck or clogged up IAC. The IAC isnt a sensor, so it works off of what the ECM tells it. If it cant respond properly to the ECM commands you'll get weird idle problems.

flotsamm

I almost forgot, a stuck EGR valve will cause a crappy idle to.

Bort62

Sounds like a big FAT Vaccum leak to Me.

Backfiring through the intake indicates a lean condition, Further backing up all your other evidence.

Its either a Vac leak, or your Fuel pump is dying. 42 psi is Kinda low but I wouldnt think low enough to cause that Much of a lean condition across the power band like that.

So what did you do to make this happen ? put in 14# Injectors or something ?

breathment

i thought stock pressure was 42 psi..

Vader

Yes, 42 PSIG is within the spec, but on the low end. For now, I'd look elsewhere unless the pressure doesn't maintain under load.

I'm with Bort. You might have a tiny vacuum leak - if you call an aircraft carrier "mid-sized". Flotsamm has a good possibility in the EGR. You might also want to temporarily cap the PCV and the brake booster vacuum lines to test the theory.

I'm a little hesitant, since with either an EGR or brake booster leak, you should be getting a MAF error as well. The PCV air is routed through the MAF, so that shouldn't set a DTC for the MAF if it were leaking badly.

As long as you have the equipment to watch the BLMs, you should also be able to check the injector pulse widths. Any data on the injector times? That might be a big clue, too.

breathment

well, weird that u said that. came home today and the check engine light came on. code 34... MAF low..


will try to have that done by tonight!

breathment

hmm. could u believe that my problems were caused by a bad connection at the starter solenoid.... runs beaufitful now.

however i am still running lean as indicated by my code scanner. so Vader, ill make another post about that..


thank you everyone for ur help..:hail:

mrr23

i'm still betting on the fuel pump for the lean condition. never did answer the question. was the 42psi with the vacuum line on or off? if it is off, then it is on the way out. or not getting enough power back there. could be bad ground wire to the pump also.

or, by the list of your mods, you may need to put an AFPR on it and raise the fuel pressure. you might be needing more fuel that what is currently being supplied at the 42 psi.

breathment

ohh sorry

thats the pressure with the vacuum line off. its at like 38 with the line on.

mrr23

should be more like 45-47 off and 42-43 on. you can try an AFPR 1st to see if it helps. when i first went from the stock 305 to a stock 350, i got the code 44 never went away until i put one on. just needed more fuel. i'll hope for you that it's the regulator and just needing more fuel because of the mods.