Fazz73jr

iTrader: (3)

I just got the car going again, and its been driving just fine. but just this past weekend it started to sputter and backfire and sometimes even stall under WOT above 3.5k. now it dosnt do it all the time, sometimes i can row through the gears with no problem. other times it will do it in first gear.

My thought is the fuel pump is diying. but its got 43.5 psi running with the vac line disconected. but, on the other hand, when the sputtering happends my wideband shows it leans out pretty baddly. tommarow when i get outta work ill try to see if i can rig up the pressure gage somehow and give her the go and see if im loosing fuel pressure.

the car is a 95z M6 383 LT1 with #30 svo red tops, xfi 280 cam, le3 heads, le intake, SLP intake, ebay LPP knockoffs, with a sock i pipe and a pos choke master muffler. Fuel system is all stock except for a new fuel filter and injectors. stock 105k opti with a new cap and rotor.

am i on the right track or am i missing something?

Thanks alot!

jaycenk

iTrader: (1)

I rig mine up through the hood so I can see it all the time while driving and testing it. Sounds like a fuel problem but you never know don't rule out possible false lean either.

Fazz73jr

iTrader: (3)

Ill do just that! Just hope the hose on my gauge is long enough.

Also I'm 98% sure it the stock original fuel pump with 106k on it. About the right time for it to start dying right?

~BuMps AloT~

iTrader: (5)

Sounds like a fuel pressure problem for sure. Check it with a mech gauge and see what that yields

95mysticta

iTrader: (4)

Had some similar symptoms with mine and turned out to be a burnt plug wire ever so lightly touching one of the primarys.

Fazz73jr

iTrader: (3)

Ill take a look at that also. But unless its the coil wire I don't think that's it. The thing nose dives when that happens,like I let off the throttle. There brand new Taylor 8mm wires. I have read somewhere of them cracking and arcing fairly quick, so ill give it a look.

Thanks for the responses guys!

jaycenk

iTrader: (1)

Taylors usually do that cracking and arching when run over the valve covers. I have had 2 sets of summit (I think Taylor makes them) 8mm wires on mine with long tubes run under the headers with no problems yet. If it's falling on it's face it sounds like a fuel problem.

Fazz73jr

iTrader: (3)

Yeah my Taylor's are ran in the stock location, under the headers. I guess I should mentioned in the original post that it falls on its face... Doh!

Fazz73jr

iTrader: (3)

well fuel pressure seemed ok, never really droped off. i thought that was it when i had the vac line connected as it would go down to about 35-38 psi under WOT. so i disconnected the vac line and it held 43.5 mostly, i think the lowest i seen it get was 41ish. but on the wideband it still did the same thing, leaned out and fell on its face.

Any reason the PCM would cut fuel? ideas please.

i checked the plug wires and all seemed fine. no cracks or burnt marks anywhere. also checked the spark from the coil to ground and seemed fine. was mostly blue with some yellow in it depending how long the arc was.

Thanks guys

jaycenk

iTrader: (1)

Question has it done this since your build or just recently?

Fazz73jr

iTrader: (3)

just recently. its been running for about 3-3.5 months now. i got the car with a spun bearing, but i got it from a friend and he says its never done that before. i rode in it about a month before it spun the bearing and everything was good then.

i deced to check for vac leaks and pull the maf for a good cleaning. i know i never cleaned it and it did not look like it had been cleaned recently. i took it for a quick spin and going by the a\f guage its running .5 to a full point richer. i only did a couple pulls and all seemed well. IDK maybe it was diry?

also i have a descreened maf that came with an lt1 i bought for it orginaly, should i try it if it continues tommarow?

Thanks for the help!

Fazz73jr

iTrader: (3)

Anyone?

:bump:

Fazz73jr

iTrader: (3)

so since i had cleaned the maf it had been running good. i was confident enough to run it at the track tonight. it did well for the shitty track conditions, my mph was up but ETs where not. ran a best of 8.4 @ 88mph in the 1/8th. ran great there no problems.

a couple blocks away from my house on the way home i see this RSX thats been talking ****. i get next to him for some fun, i roll out 1st gear to go from a roll @ about 15-20mph and the SOB started doing it again!! just leaned out and fell on its face like a fuel cut. i push the clutch in and the rpms drop, then pop revs up on its own to about 1500 the shoot back down and pop. WTF is going on?!

I hate to jump on the bandwagon but could it be the opty? its got about 105k on it, but has a new cap and rotor. also thinking maybe somehow it got a bad flash? theres been at least 2 time i can recall that it would go into DFCO going down hill for a good 20-25 sec and not come out. Id hit the gas and noting, i would push the clutch in an it would die. i would just trun the key off and restart and it would be ok again. IDK what to think now...

HELP

lt1slowz28

Randomly cutting out and going lean tells me the injectors are losing signal to fire which very well could be the opti... or crank position sensor but.... eh opti


Since you said cleaning the maf helped try unplugging it and driving it around albeit with a cel you can eliminate that from being the culprit if it continues to act up

Fazz73jr

iTrader: (3)

Will try disconnecting the maf today. My car is a 95 so there's no crank position sensor.

Thanks for the response, keep them coming!

Fazz73jr

iTrader: (3)

I'm noticing its happening more when I roll into the throttle before it goes WOT. Could it be the TPS?

I have not been able to log it as my laptop is down for the count.

Any help/suggestions are welcomed! Thanks!

Wicked94Z

iTrader: (26)

if you can get a log I can see where the tune is at, or maybe we can meet up this weekend and work on it. I can't remember off the top of my head what the PE tables looked like.

speedZ28

I hooked a gage to mine it would say 39 psi at wot it would drop to 31 psi win i pulled vacum line off it went to 45?? Mine to out to be fuel pressure regulater? So it could be that to!!

camaro-94-z28

iTrader: (3)

My old camaro started doing that, when the opti was first starting to go.

Fazz73jr

iTrader: (3)

That would be awesome! but my laptop **** the bed about 2 weeks ago. probably wont get it back till next weekend or so. i do have a WOT log i did just before the laptop died. i noticed my o2 sensor readings are pretty far off from each other. wondering if i need new o2's. i can send it along with the other logs i have from that night. altho it was running good that night.

I thought that was it for sure when it first started happening, but mine stays at or above 40 psi at WOT. even when the sputtering happends. thanks tho!

I kind of have a gut feeling its that as well. Its on the stock orginal opti with 106k and counting. i did put a new cap and rotor on it. maybe its time to put my spare unknown mileage opti on or get a new one from Chandler Motor Sports...

I tried the TPS i had on a spare motor that was runing fine and it made no differacne. thinking maybe ICM or my o2's.... idk

Thanks for the responces guys!! keep em coming!