Well I thought I was heading to the track tonight. But a Gremlin that I had been fighting awhile back is at it again.

This is what I have going on;
As the rpms come up and boost goes up, I get a miss fire that is bad enough for the ecu to kill a couple of cylinders for a couple of seconds, even after I back out of the throttle. Car rpm's up fine under normal or low boost driving (below 20psi) all the way to red-line without a hic-up. Turn up the boost and it starts to come in. 2 plugs look nice and clean, 2 plugs are dark.

This is what I have done to try and fix it;
Replaced both coils and power transistor today, put BPR7ES plugs back in (gapped at .026), replaced plug wires and cam sensor about 6 months ago which was throwing up a fault code also (for this same problem) . None of this helped.

I have Sunoco 116 in the tank and am getting no knock. Oh yeah I forgot, if anyone wants to know how tough the 2g headbolts are, I can tell you pretty damn strong. My Profec-b got out of adjustment and on the first few times I hit the boost to try and see how it was running it was hitting up to 29-30psi and pulling hard when it wasn't miss firing. Damn if I could just figure this shit out. No, I don't plan on running 29-30psi on this stock 2g.

Let the games begin :headache:

are you running 20 psi daily driving on a stock 2g?

no, nornal is 14-15psi

Stock headbolts and your pushing 25+ PSI?? Ughh I dont think that the 2g bolts are much, if any, stronger than 1g bolts...

As for the problem I dont know sounds strange... Its not fuel cut?

Running DSMLink which removes the fuel cut.

http://www.dsmstyle.com/forum/index.php?showtopic=25

Not everyone knows what you have done to your car.

It definately sounds ignition related. Have you tried reseating the wires after the engine is hot? Sometimes they can pop off because of the air expanding if you put them on when it was cold. Do you have a fuel pressure guage? Maybe the fuel pressure is dropping as demand increases?

The 92.5+ bolts are weaker due to being a 1mm smaller.

Bad injectors? Are they black from fuel or oil?

Semi-blown headgasket? Might only be blown enough to cause problems at high boost, but that might just cause it to overheat a little and push coolant, but not misfire.

Are you I/C pipes free of oil? A little oil from a slightly blown turbo seal or accumulated in the intercooler can cause misfires under boost.

So 92.5+ which would b all 7 bolts are acutally weaker than 90-92.5? So would his headgasket have blown? CVD is probably gone... but he atleast has some other problems.. like overheating.. its still runs good though...

Vicous- How could you not even obey your own posted rule about mods and stuff? :lol:

Have you tried replacing the ignition control modual?

I figured everybody knew what was on my car from the Featured Members post. :uh:

I have replaced the ignition transistor module.

I was having this problem before my car hit 29-30psi.

It still drives fine, no loosing coolant, no miss-fires under light boost.

The 2 plugs are dark from fuel, probably from miss-firing.

Modifications so far:

Engine · HKS 272/272 intake/exhaust cams - Fidanza Timing Gears - Balance shafts removed - Fluidyne radiator - FAL Twinline fans - (NOTE: I'm still running the stock 2g intake manifold, cylinder head, shortblock, and throttle body)

Fuel/Ignition · DSMLink v2 ECU Datalogger/Tuner Package (If you are not running one of these, you should be!!!) - MAFTranslator w/GM 3.5 LS1 mas - Apex-i S-AFC (only for display of rpm & tps) · DynoTune Digital O2 Meter - 750cc FIC Ball/Disc injectors · Upgraded fuel pump - Fuel pump re-wire w/10 gauge wire · MSD 8.5 spiral core wires - NGK BPR7EIX (Iridium) Plugs gapped at a tight .028

Turbo · VPE GT3056 TO4E B/B Turbo · Tial 40mm External Wastegate - VPE S/S O2 Housing Routed for External-Internal Dump - DN Performance Tubular S/S Manifold · HRC Upper/Lower Intercooler pipes · Dejon Tools intake pipe - K&N air filter - GReddy Type-S BOV · GReddy EGT · Autometer Phantom Boost Gauge · GReddy Profec-B Boost Controller · GReddy Turbo Timer · BIG GReddy 24R FMIC (upper part of bumper opening cut out behind upper black strip for improved air flow to FMIC) · Catch Can breather element

Suspension/Handling · Eibach Pro-kit 1.5" springs which have been cut to lower the car a total of 2 inches · KYB AGX 4-way adjustable shocks · Ingalls adjustable camber kits at all four wheels - Front/Back strut tower bars · 18x8 Rays Engineering/Volk Racing AV3 wheels · Nitto NT555 225/40ZR18 tires · Metal Master brake pads

Clutch · Clutch Masters 2500lb w/Ceramic 4-puck Sprung Hub Disc (custom kit good for 600+ HP) · Clutch Masters Billet Aluminum Flywheel w/Steel Face

Exhaust - RSR 3" downpipe · HRC 3" hi-flow cat · Apex N-1 3" cat-back exhaust

Since I really don't know much about this tech stuff I'm going to ask this, is there any sort of relay (or something serving as a type of relay) somewhere on the fuel system that when you're demanding the amount of fuel to match 29-30 lbs of boost, something isn't right causing the relay to shut down a couple of cylinders? I'm probably talking 100% out of my ass but it was an idea....

The ecu will kill cylinders that miss-fire excessively.

The 29-30psi is not causing the problem. It does the same thing at 20psi.

Well it sounds like you have covered everything ignition related for sure. With it just happening in 2 cylinders, I would agree with shane on the possibilty of a head gasket or something similar. Maybe do a leak down test on all the cylinders and compare at high pressure levels to see if something is leaking under boost. Maybe the head bolts are stretching enough under pressure to allow a leak only after you are over 20 PSI.

I may have found the problem, looks like the ASS that worked on my transmission under warranty at Mitsu cross threaded the upper bellhousing bolt that the negative battery cable attaches to. It sticks out about 1/4 inch and the cable end just wiggles on it. I can't get it out or in to tighten. STUPID FUCKER at Mitsu.

Yeah, I'd guess ignition, and I'm guessing both black plugs are on adjoining cylinders for one of the two coils. A bad ground could cause that. Aren't you getting a CE code?

No codes

Are the fouled plugs 1 and 4 or 2 and 3?

I don't actually remember which cylinders they were from. I was trying to get to the track and just pulled them out quickly to re-install the BPR7ES plugs I had to see if that helped because alot of people want to say the BPR7EIX (Iridium) plugs don't work well. Didn't make a difference though.

The car will be back at Mitsu Monday morning. I told them I am not paying for their fuck up on that bolt and they better not scratch the fucking car again. Everytime it has been there something happens to it. If it wouldn't have been for the warranty, it wouldn't have been there in there first place.

It's not a big issue if it is the engine itself. I would just like to know for sure before the new engine arrives. I'd rather figure this problem out on the old motor vs. fighting it on the new engine if it is something else.

Did you get the problem solved yesterday Mike?

It's at Mitsu now. The bolt in question is not a bell housing bolt, but the starter bolt that is stripped out. The bell housing is missing a bolt that goes into the block also.

If this doesn't fix the miss, I'm gonna swap some other injectors into the car and see what happens.

Sounds like your laptop controlled AFC is not doing what you want. I say the DSM link is the problem. Unless you changed nothing on the dsm link and this started up for no reason. And this ground you are talking about is for the starter, unless they plan on the ground for the ignition system to go threw that bolt.

~John

Grounds can be a funny thing. I used to get a bad O2 code in my CRX because the ground for that particular circuit was to a bracket on the tranny right next to the starter. When I swapped trannies I forgot to clean off the bracket on the used tranny I put in there where the ground goes. Grounding could definately be a small part of it.

I also have to go with one thing JET brought up, monitor fuel pressure at all boost levels. We are running into a problem with a Safari Van that wouldn't run under load. It ran fine when it idled (kinda stumbled a little but not bad) but when you hit the gas it killed. We dismantled the throttlebody and found the regulator spring broke into 3 pieces. I'm not saying yours is broken but maybe the pressure isn't high enough to keep up with what's needed at the higher boost levels. I could be off the mark here, but I didn't read anything in your mods about an adjustable FPR.

I'm starting to believe it is an injector. I got it back from Mitsu, but have not had a chance to run it under high boost yet, need to buy some more 116 oct. The reason I believe it is going to be an injector is because my car is getting hard to start, and when it does fire up, it misses on a cylinder for a little while until it clears up. Also have a problem where it will idle fine with my LTFTlo will be at a good -1.0 to +1.0 range and then it starts to cut up and the LTFTlo drops to -12.5 to try lean it down. Also keeps trying to stall at a stop. I have a VPE hi flow fuel rail and 1:1 AFPR with the fuel gauge mounted on oder and am waiting for it to come in. That way I make sure the fuel pressure is set correctly. Now as far as the fuel pump keeping up, I may have to get the Walbro 255lhp or higher flow pump. Not sure which way I'm gonna go with it. Maybe a Cosmo pump. I talked to Scott at VPE about the injectors and he is going to send me out another set to try.

DSMLink is working fine. The AFC is not controlled by my laptop. The AFC was only there originally to deal with the hacked maf at idle and low speeds. Since I installed DSMLink v2, the AFC is only being used for quick glance readings while driving, no adjustments are set for fuel on it. It shows rpm, throttle position, maf frequency and compensation (which reads 0 all the time) while driving.

I was saying the dsm link is a AFC you run threw a laptop to make changes. The stock ecu has the final say, so I think its a big waist of time. It sounds like the problem came out of no where. So injectors it is.

~John

I don't know about the DSMlink, but the AEM gets really pissed off if you try and use an AFC with it. When I first installed mine I thought it would be ok if I set everything to 0, but it wasn't. It took me a while to figure it out. Just another possibility.

The DSMLink does not work like an AFC at all. With an AFC you are fooling the ECU by modifying the airflow numbers. With the DSMLink the ECU sees the true airflow numbers and you are changing the fuel inrichment inside the ECU itself. It works closer to a standalone than to an AFC. You don't have the grids like you do in a standalone because that is not how the stock DSM ECUs even handle the fuel.

It is done a little differently in the DSM ECUs than in a standalone or even a lot of ECUs like Hondas where is has specific pressure vs rpm fuel maps. The way the ECU handles idle/part throttle is that it mathmatically calculates what a 14.7:1 airfuel ratio would be based on injector size and airflow from the MAS and spits out that much fuel. It uses the O2 sensor during those times to make adjustments for how far it is off. The amount it is adjusting it are the fuel trims you see in DSM dataloggers. For higher loads it uses fuel enrichment maps to add fuel on top of the calculated values and the O2 sensor is eventually ignored. There are 12 of these fuel enrichment maps in the ECUs. There are also 12 timing maps. A lot of the stuff in the 1G/2G/GVR4 ECUs are the same basic code, but with slightly different enrichment and timing maps. Under WOT with a turbo flowing anything even close to a decent amount of air your going to be working off of the 12th map.

Any update on this Mike?

I'm gonna swap out a set of new injectors I bought from ._guest_. and see what happens. If they don't fix it I will have a new set of injectors for sale. :uh:

I'm gonna swap out a set of new injectors I bought from ._guest_. and see what happens. If they don't fix it I will have a new set of injectors for sale. :uh: [/b][/quote]
Any news/progress?

I just recieved the injectors from ._guest_., but have not put them in yet.

I recieved an email from DSMLink yesterday saying that the first 100 v2 chips had a bug in it (yeah, I was in the first 100) so they are sending me out another chip. So I'm gonna wait and see what happens with the new chip first.

Awesome, hopefully that will take care of the problem. Let us know when you get the new chip in. :)

I would look at the fuel pressure under boost conditions. Excessive fuel pressure at the wrong time can cause misfire.

0.026 is a bit close for the plugs. If you run boost beyond 20 psi Iguess you may have to run the gap down like that, but 0.030 is a normal "street performance" DSM gap. You might want to try opening the plugs more and see if that changes things.

It may be that the engine isn't tuned just right, too, but I suspect excessive fuel pressure.

Rick