Heavy Fuel Cut

[BlackMount]

I've got 1990 Laser RS Turbo

I've been running into some heavy fuel cut issues.

I get fuel cut at about 3-4.5k RPM's regardless of Gear or Speed, and will not let me go accellerate at all My top speed is about 65mph interstate because of the fuel cut. I have a stock and aftermarket boost guage. stock one reads 14 PSI, aftermarket never moves past 11 PSI most. I am running stock boost at the moment as I traded my boost controller for a 16G and BIG FMIC

If I drive the car for about 15-30 mins (depending on how much stop and go I do) the fuel cut starts to go away and eventually there is none at all. doesn't matter how much gas I'm giving it. sometimes when it starts to get better if i mash the gas down the fuel cut goes away and I boost perfectly normal.


Sometimes at Idle I get a CEL, and there's also a miss at idle. I'm going to get the CEL checked, and also try and diagnosis my miss at idle today.


My Gas mileage is also horrid, I got about 175 miles to a single Tank of gas this week @ 93 Oct. the week before I got about 260 to a tank of gas @ 93 Oct, and I did alot more "Sprited" driving that week then I did this week. been a mix of interstate\highway and stop and go.

255Walbro Pump (Not Rewired)
Stock Injectors
SMIC
14B @ Stock Boost
New Plugs (maybe the wrong ones I heard some one else had that problem)
Tubular Manifold
Magnaflow Muffler
K&N air filter
Open Air Can mod.
Turbo Timer. (BLITZ FATT set @ Auto)

Please help this is very obnoxious.

 

[GRAVEDIGGER]

I would be looking at the plugs and wires right away. If you haven't changed the wires in a while or don't know when they were done, I would replace them. Also get some NGK's if that is not what you have.

 

[BlackMount]

I got NGK's but the cheap ones, and I don't know if they are the Non Turbo or Turbo (heard there is a difference). they are the 1.99$ plugs. i will get better but short on cash. wires are fairly new.

 

[SrKegler]

Sounds like the 255 fuel pump is overrunning the stock pressure regulator. Plugs are probably fouling out.

 

[GRAVEDIGGER]

The plugs you need are part # BPR7ES. I think they have been recently changed to # 5534 though.

 

[adamtsi]

I had the same problem in my 4g61t colt and i put a new set of ngk bpr7es plugs in and gapped them to .028" and now she runs like a champ

 

[BlackMount]

Sounds like the 255 fuel pump is overrunning the stock pressure regulator. Plugs are probably fouling out.

It's running rich, but not fouling the plugs. I pull them, and they are black but dry.

The plugs you need are part # BPR7ES. I think they have been recently changed to # 5534 though.

I will try that. Hopefully it works. I will also check which plugs I have when I get the chance.

 

[GooeyGus]

Fuel cut and misfiring are two very different things.

Fuel cut at WOT will make you poop your pants the first time it happens.

IF it is truly fuel cut, you need to start looking for leaks. If you are losing a ton of your air out of a leak, you can hit fuel cut at relatively low boost levels because you are still pulling in a ton of air.

If it is a spark problem, then new plugs and wires are your best bet. If the problem persists, keep working your way through the ignition system.

 

[BlackMount]

i noticed out on the road it wont let me accel past 3k rpm. i got angry because i was going so slow so i pushed in the clutch mashed the gas. the result was a nice healthy boost until i had to change gear. 6.2k rpm shift btw. i noticed i dumped a metric shit ton of black smoke into the air.

so my problem is either too much gas (cause of my 255 fp?) or not enough spark (my cheapo ngk)

ps if i attempt to rev the car in gear or nuetral it makes a noise that sounds like dsmluanch or 2step or whatever its called and pins the revs @ 4k.

and in order to identify A from B is Fuel Cut the like rev limiter i hit at about 3 or 4k that sounds like 2step? or is the fuel cut the heavy bogging and jerking i get from time to time at about 3-4k?

EDIT: I have the wrong plugs I have BPR6ES not BPR7ES. 1 number off. None of the Auto Stores around here carry BPR7ES NGK Plugs so I am ordering them off line. Hopefully that fixes my issues. I'll let you guys know, and if so we should sticky this thread or something because I know 2 other people with this same problem in the Local DSM Scene down here.

 

[SrKegler]

Are you showing any CEL's? The BPR6ES is the plugs I use. The 7"s are just a heat range colder. If you have a logger, that would help to narrow things down.

How about the ECU. Have you checked it out. The 1Gs are notorious for blowing capacitors and sensor grounds.

 

[JEFFREYCASTGSX]

No one has yet to mention a boost leak test? IC Pipe Tester

 

[GooeyGus]

No one has yet to mention a boost leak test? IC Pipe Tester

I did

 

[juanpac0]

You're running super rich, and your timing might possibly be off.

 

[cemille01]

mine was just doing the same thing!!!! i changed the fuel filter, changed the plugs and actully found that mine were not even tight from the previuos owner put new ngks in and gapped them to about .028 of an inch, they were .038 from the original owner and cleaned they plug wiresreal good with electrical cleaner, and put it all back to gether and viola!! no more fuel cut give this a try it worked for me

 

[BlackMount]

mine was just doing the same thing!!!! i changed the fuel filter, changed the plugs and actully found that mine were not even tight from the previuos owner put new ngks in and gapped them to about .028 of an inch, they were .038 from the original owner and cleaned they plug wiresreal good with electrical cleaner, and put it all back to gether and viola!! no more fuel cut give this a try it worked for me

That's what I am going to try. I had to order the plugs because no place local carried them, they didn't even list them to order VIA warehouse. Until my plugs get hear I am going to pull them and re-gap them at 0.028

I've pulled my ECU, and there's nothing I can tell visiably, I don't have any spare ECU's just laying around so I cant exactly try switching it out. But I did let my buddy borrow it for a day his GS-T that he wasn't having any similar problems.

I do get a CEL that comes on at idle but doesn't always come on. It usually only comes on after boosting and then let it drop to idle and the car has to have been running for a good 20-30 mins.

Coil Packs are new, Wires are new (but Cheapo ones), Spark Plugs are new but the 6ES and not the 7ES. Like I said I'll see about regaping them today. Hopefully that helps. I doub't its my Fuel Filter because Obviously I'm getting enough fuel.

Just a Update. I half solved things.

I wrapped all of my IC hoses w\ duct tape (looks kinda ricer but it was neccesary and only temporarily till I can afford new hoses. I'm Broke) because the had all seen better days from my inspection yesterday so I figured maybe I have a boost leak. that helped my unstable idle become stable. Then I messed with my Vacuum lines, and changed some things around, and now I'm pushing 15 PSI of boost w\o a boost controller (????) I noticed now that I'm loading my motor with more boost the miss isn't near as bad, and it wont miss when I hit full boost at all so I can rev it all the way up. it only misses randomly at idle, and at low mid rpm's when I'm not in boost.

so my problem is for sure too much fuel or LACK of air

So leaky injectors. or too powerful of a Fuel Pump is my next choice. I'm going to try to get some new hoses for my IC this weekend and fix my shit.

I also re-gapped my Spark plugs to .28, That didn't do anything. I noticed the tips of my plugs were starting to turn brown from black now. dunno why. If it is my Ignition System I think it is my Plug Wires.

 

[BlackMount]

Found out the problem.

Turns out it was\is my ECU.

I put it in my buddy's GST again today, and it was doing the EXACT same thing as my Laser. I guess last time I just wasn't paying enough attention and what not.

so resolved.