New issue. smooth in boost at first, then later on sputtery/misfires...;

[WDRacing]

The odd thing is, cars in general will run fine when they are rich. You'll get less power, less mileage and possibly end up with fuel in your oil if it's too rich, but they usually run great.

I've noticed more issues when I ran lean for some reason or another.

I friggin hate troubleshooting from the bench

[zerepdivad]

^ i hate snow being on the ground and not being able to go work on this pile of style of a vehicle.

[Loch Ness]

check ur grounds.....resistance shouldnt be higher than .2,injectors might not be able to flow consistently at that boost level without an ecu tune.......do u still have stock injectors?

[zerepdivad]

Well i got around to doing my compression test today. It's been sitting for a while with no driving but the occasional move from the garage to drive way.

Here's my results.

cylinder 1- 130cylinder 2- 130cylinder 3- 125cylinder 4- 145

I take it this is likely what is causing my issues. Kind of odd though since they're close to eachother i'd imagine it'd just be weaker and not have these issues. kind of sucks, but i can probably still pull the turbo stuff off and sell it since it'll probably be just fine for an na daily driver or something like that, since it starts up and drives perfectly fine with no boost.

[WDRacing]

Was the motor at operating temp when the test was done? Also, low compression isn't going to cause any noises, however, knock will cause noise and lead to low compression.

You really should do that test I recommended. Marking the dizzy, retarding timing, then drive, then reset to stock, drive and note the results from both drives.

Just verifying your timing is at 20 degree's doesn't do anything to check for knock. I ran my RB20 for a year with low compression on #6. By low I mean 35 psi low, I just turned the boost up and adjusted for knock accordingly:bigthumb Not the best method, but I didn't want to swap the motor at the time and wasn't about to remove the damn turbo.

WD

[zerepdivad]

Test wasn't at operating temps. It was close to 0 degrees out when i did it in my garage. I started it for like 30 seconds just to verify my battery still had enough charge and whatnot.

I do recall doing what you said about retarding the timing a bit and it still did the noise, and acted about the same.

At this point i'm very frustrated as to what else to do. What are the chances that it's this emance tune i'm using causing issues? I don't want to be the type to point fingers at stuff when i can't figure it out. But is there any way to test it?

[Afields81]

Just last week I was having a similar problem. I the car would start up fine and go into boost perfect until I got to around 5k rpm and then it would just back fire like hell. I searched for around 2days straight and everyone kept saying it was my ignitor, or my plugs or my fuel oo yea and my maf I checked everfything and it turned out to be a bad ground on my coil pack harness. Also you should ground your fuel pump straight to the chassis. The stock wiring for the pump sucks. Its worth a shot.

[ghx407]

I had a similar issue several weeks ago; it turned out to be spark blowout. Here's the thread, it might be of some help:

zer...owout

[WDRacing]

Man, I wish I knew you were using Emance. I would have said replace that first thing. I have heard so many horror stories now. It's almost hard to troubleshoot anything else knowing that the ECU could be causing all the issues.

Lose that thing homie. A stock ECU with a FMU is 100XXX better then a Emance IMO...lol.

[D-UNIT]

IDK dude so many things could be wrong, just go slow and cancel out all options. Now my car only sputters when I'm at 0.0 psi +/- .1-2 psi. At Full vacuum and at full load there is no problem but at part throttle at 0.0 psi = misfire city. Weird.

[zerepdivad]

Yeah i was thinking the ecu but it was working just fine a few thousand miles prior to me going to the track. Here's the thread from there that i made right away after it started happening...zerothread?id=450794

I was planning on swapping out for an efi specialists ecu but then i started having these problems and put that on hold in case soemthing is really messed up.

[Romeo_rus]

What BOV are you using?

[zerepdivad]

I was running a 1g crushed dsm bov but am now running a knockoff gredy one. Boost leak tests up to like 20 psi with no leaks, sounds kinda funny but it works.

[Romeo_rus]

I had the same problem on my rb25det... that time it turned to be CAS... I know that you have a KA, but I'd try to check that thing too... And get a better BOV with faster response

[zerepdivad]

Yeah i checked that and swapped out to another good distributor i had in the garage and same results. I just put new plugs in it, gapped them to .o28 and drove it around for a few minutes and it was hard to tell if it was doing it or not. It's so cold here that even if i'm going like 35-45ish if i get on it and it gets into boost my tires spin and it never does the sputter when i break traction. I was going to keep driving to see if maybe my tires woudl warm up but it started overheating and i realized one of my fans wasn't turning on for some reason. That should be easy enough to figure out though.

[D-UNIT]

I swear whats happening to your car is happening to mine. I notice it gets worse on sweeping right hand turns. I think I have a harness gremlin near the ign coil and maf split. When I jiggle the wires in that area sometimes it gets better and sometimes it does nothing. I've had my car hooked up to a snap-on scan tool and had no weird voltage fluctuations but that was at idle and not driving. I'm thinking ign coil harness or resistor gonna check those next.

[zerepdivad]

Yeah this crap is annoying me, and mainly because it's so cold here that i can't even work on it. I'm ordering a blaster coil off somebody on here for cheap, and am getting a new set of 550cc injectors, as well as an enthalpy tune. I figure i was going to get them eventually so i may as well get them now in it's downtime. Don't want to throw any of it on besides the coil until it's all straightened out though.

[D-UNIT]

I tell you I don't think its your coil. I tried three different blaster ss coils off of perfectly running donor cars same problem on all of them. Its crazy cuz under full load no problem. Hell I just beat my friends lightly modded g35 (I/plenum spacer/E) yesterday. It was funny we went from a roll, he was in 2nd and I left it in 4TH!!! at like 2000rpm (35mph?). He jumped about half car on me and then I passed him by 4500rpm in FOURTH GEAR! But once I let off and went to part throttle it started mis firing so irrating!!!!
Modified by D-UNIT at 6:55 PM 2/7/2010

[scotttak]

hmm...only when its warmed up? i would think its the tune, maybe o2 sensor, or coolant temp sensor.

[madd ocx]

what spark plugs are you using? and whats the heat range? my car was doing the the same thing a while back while under boost it would bogg and sputter. then i changed out my plugs to the correct heat range and it ran fine..

[D-UNIT]

I found I had a slightly ripped coupler near frame.

[zerepdivad]

I found I had a slightly ripped coupler near frame.

Nice to hear you got yours figured out. Don't think that's my issue though since i boost leak tested over and over and didn't seem to be it. Hopefully mine ends up being something that simple. Just waiting for the snow to be gone here so i can work on it comfortably.

[D-UNIT]

no no NOOOOOO!!!!!! it came back!!!! It wasn't the coupler , so I hooked it up to the scan tool again. This time I noticed a wild sweeping voltage spike at the MAF. at idle .78v and then it spikes to 2.3v and 1.4v so fast you can barely see it. good thing the snap-on solus has a high refresh rate. Everytime it spikes I get a sputter. I was told my MAFs ground might be bad supposely happens to SRs all the time. Need to splice and reroute and make sure ground wire is 0.4 ohms. Did not try yet. gonna call JWT and my maf company first.

[D-UNIT]

yep had a bad ground connection at the MAF. the pin recepticle was whored out and barely touching the ground pin so I squashed it closed and now it run 95% better, 95% because I'm still getting a random misfire now and again. But no more sputtering!