fuel cut I have no idea whats wrong. help

[Merkles]

I have no idea what is wrong with my car. My mods are listed in my profile. Here is my problem. My car rips until 15psi where I have my boost set and holds until anywhere between 4500 and 5500 rpms then hits fuel cut. I have no clue why. I ran a boost leak test and had 1 tiny leak at the throttle body but I fixed that and I changed my spark plugs and put new ones in. Any ideas?

 

[Merkles]

aw man, i really wanna wait for DSMlink v3 to upgrade fuel controller...

either way i swapped out my ECU with my sisters GST and still does it

You know you can buy V2 and pay a small upgrade fee when V3 comes out right?

 

[DSM_PWR]

yea but there's so much controversy on that topic, price, re socketing ecu, new cable. etc... id rather skip all that and wait for it.

 

[hdoerr]

After spending some time with DSM PWR troubleshooting his car last night I believe it is fuel cut. Here is my reasoning: We did a comp. test and while not great it averaged out at 135 per cylinder. We gapped his plugs to .27 from .22 and then .32 doing some pulls per gap just for shits and giggles to eliminate that variable. During the .32 pull I took a look at his AFC to get an idea as to what the fuel adjust was and here is where I believe the problem comes from. His MAFT is zeroed out at the point where the fuel cut happens but his AFC was set at +30% from the 3400 rpm point and up. I turned it down to +10% and the car pulled past the previous 4500 - 5000 cut off all the way to the rev limiter. The wide band was reading high 16 to 1 ratio so I added more fuel to +20% and the car started to hit fuel cut again, later than before but it still was lean and cut at about 6000 -6500. So to confirm I set it back to +30% and we were back in the same boat as when he got to my house. Call me crazy but his 650's should not need to be +10 - +30% larger via air fuel correction because that will cause MAF over run I.E. fuel cut. I think DSM PWR is correct by planning for link. It will be able to tune this problem out. I have read that AFC and MAFT don't play well together and wonder if that is the underlying problem.

 

[v8s_are_slow]

Okay sorry guys, I see I missed a few post as I went back and read everything all over again from the beginning.

1st, about the leaking gasket and using the wideband. I dunno about 2g's, but personally, I don't even run a stock O2 sensor at all. I disconnected it and threw it in my tool box and then just threw in my wideband in the stock location. Reason I did this was because I was getting tired of worrying about having exhaust leaks and not knowing if my wideband was reading accurately or not. I've been running just fine.

2nd, Dsm Pwr, I thought you sold your afc??? Confused since you're still tuning with one? Borrowing one or something I guess? Never heard back from ya about the base timing so we still don't know where that's at. Also, if wideband is saying lean, it's probably lean. Add fuel. You're running a 50 trim and just because you throw in bigger injectors doesn't mean it's magically gonna run rich when you're using a piggyback to compensate. I have a 50 trim and 1000cc injectors and I can still run lean if I tune it wrong.

Now I'm gonna "assume" you're just using the MAFT for tuning and nothing else. Remember now, just because there's a chart that tells you where to set your base and aux knobs for whatever size injectors you have, that does NOT mean that's where they need to be. I'm not sure if you still have your high zero'd out or not but if you're lean at higher rpm's trying turning it to the right. Also, let's say for a second that you're tuning with the afc, you still have to have the base and aux knobs set close to where they should be. You may still have to adjust those to get your global settings close to where you need them.

Here's what I do because I DO NOT have anything for datalogging (I have a dsmchip and all I can view is my boost gauge that was converted to a knock gauge). As for my idle, I really don't give a flyin **** if I'm running rich or not because WOT is where it really matters to me. I'm running around 11-12 or so at idle on my wideband. As for mid and high, if I'm lean at WOT, I just turn them both to the right and keep the adjustments about the same for both knobs. They say that the mid can be a bi*** to tune so I just try and avoid any problems by making sure I keep the mid where my high knob is at. So far so good.

I realize you don't have a chip to compensate for your injectors and the deadtime so that doesn't help you any. Wondering what your plugs looked like when you changed them. Before I was thinking a spark issue but now I'm reading that it's going lean. Add fuel where you're going lean (just don't even bother looking at your trims right now incase your O2 sensor is jacked up. Just look at the wideband) and adjust according to what the wideband is telling you. That's what it's there for anyway right? If you're adjusting as much as you can with the low, mid, and high knobs and it's still not making a dent in it, you may have to adjust the base and aux knobs to add more fuel overall and then retune with the low, mid, and high's again. Hope this helps.

I know you plan on going with Link which is a good idea, but sure you wanna run good till you're able to get it. Let us know exactly what you're tuning with and how everything's looking so far.

 

[v8s_are_slow]

But what if you have this same problem with the sputter and no MAFT or GM MAF? Ive been stuck on this problem for like 8 months and strapped for cash. I thought it was an ignition problem too. A/F dropps down to 10. I kinda gave up an now drive the truck everyday. But i think this thread made me want to try to fix it again. Anyone have any ideas?

Also my mods........
2.3 stroker
Big 16g (internally gated)
660cc injectors
walboro 190
magnecore 8.5 wires
NGK br7es (go through them like water)
SAFC
Wideband 02
and more in my profile....

any help would be greatly appreciated

If you're going thru your plugs like water, I'm guessing it's because you're fouling them out? What size maf do you have and where's all of you settings at on your translator, including your dipswitches?

 

[DSM_PWR]

Yes i sold my SAFC but then i bought another one because i noticed i wasnt able to tune as good with just the MAFT alone. Now im pretty sure it has to do with a piggyback on piggyback. Last night i set the MAFT AUX on 4 and left everything else alone (trying to get it for stock 450cc) Then on the SAFC i set the LO and HI settings as best i could without my logger working and i was able to reach 5500rpm. earlier that day i was only able to reach about 4500rpm. BUT im still having to add fuel which shouldnt be happening. I noticed that my AFPR gauge has let out all the liquid so my guess is that its not an accurate reading. My Base fuel pressure is probably low

 

[v8s_are_slow]

You should check out the forums at FULL THROTTLE SPEED - Store Front Page. Personally, I've never used an AFC and of course haven't used one in conjunction with a maft. But I'm sure there's plenty of guys on there that could maybe help ya out as far as tuning with the AFC. I know the AFC isn't hard but I just haven't used it so don't wanna give any advice on anything I've never dealt with. But it's obvious you need more fuel if your wideband is saying it's lean. Good luck man.

DSM MAFT Support - Full Throttle Speed Tech Support

 

[Merkles]

You say that your going to upgrade to DSMlink V3 so why don't you get the socketed eprom ECU now. Then get a keydriver chip from Jeff at DSMchips to use as your base tune and go from there. Then you can just buy the DSMlink V3 when it comes out and you will already have the ECU. Since I put my keydriver chip in a couple days ago my car has never run better.

Just a suggestion. Not to mention you get monitor your knock and all the other goodies that come with a stage III chip.

 

[v8s_are_slow]

I was thinkin the same but he'd have to pay $140 for a temporary usage. But yeah, it'd run better. I'll tell ya, I tried throwing my stock ecu in my car with the 1000cc injectors (to try and diagnois a problem) and it fouled my plugs in just a few minutes. The chip definitely helps.

 

[mmmmbst]

If you're going thru your plugs like water, I'm guessing it's because you're fouling them out? What size maf do you have and where's all of you settings at on your translator, including your dipswitches?

I have the stock 2g maf. I have to wait till payday to get the 3in GM MAF and MAFT. I was told that it would possibly be my problem. I just hope I dont drop this money and find out that this wasnt the problem. The car sputters also and the A/F drop instantly to 10.0 and since the lowest on the UEGO is 10.0 i cant tell what the actual A/F is. it seems like its going way low. I kept taking away fuel from the afc and barely see changes. Im almost at the limit of the afc and its still rich as hell. the car sounds like its trying hard and its holding 20psi but its barely pulling.

 

[v8s_are_slow]

I have the stock 2g maf. I have to wait till payday to get the 3in GM MAF and MAFT. I was told that it would possibly be my problem. I just hope I dont drop this money and find out that this wasnt the problem. The car sputters also and the A/F drop instantly to 10.0 and since the lowest on the UEGO is 10.0 i cant tell what the actual A/F is. it seems like its going way low. I kept taking away fuel from the afc and barely see changes. Im almost at the limit of the afc and its still rich as hell. the car sounds like its trying hard and its holding 20psi but its barely pulling.

Have anyone that'll let you borrow their maf so you can diagnois yours? I see you're only running a Big 16g. So nothing "too" major in there. Tried throwing in your stock injectors to see if that helps? If you don't run rich with those, you might just need a chip as well to compensate for those larger injectors. Just a thought. Sounds like you have a pretty basic setup so there shouldn't be that much you should have to check for. And make sure you have good non-fouled plugs in there before you try it out. Otherwise the fuel won't ignite very well and you'll still think you're having problems.

 

[mmmmbst]

Have anyone that'll let you borrow their maf so you can diagnois yours? I see you're only running a Big 16g. So nothing "too" major in there. Tried throwing in your stock injectors to see if that helps? If you don't run rich with those, you might just need a chip as well to compensate for those larger injectors. Just a thought. Sounds like you have a pretty basic setup so there shouldn't be that much you should have to check for. And make sure you have good non-fouled plugs in there before you try it out. Otherwise the fuel won't ignite very well and you'll still think you're having problems.

I wish i could. I have not seen a turbo dsm in charleston since i got stationed here. I also dont have the stock injectors either, i sold them to my buddy with his turbo civic and he sold the car. The weird thing is that when i dropped the new motor in and broke it it and started street tuning it, it was fast as hell. then all of a sudden (4 days later) it started falling on its face. Anyone have a MAFT and lives in the charleston, sc area???? Theres only one tuner shop around here and ive heard so many stories about how bad they are so im trying hard not to have to result to go there.

 

[mattdev]

Hey DSM_PWR,

In my experience my MAF-T runs lean for whatever injector size it's set to. Try lowering the injector size (richen up the base). Try doing some fuel trim logs w/ the safc zeroed out so you can set a base w/ the maf-t. Then use the SAFC for fine/rpm tuning

I've had a terrible time w/ my MAF-T and it is almost worth throwing away. It's inaccuracy being the main issue. ie I have 650cc FIC Injectors, my Translator is set to 480cc just to get a level fuel trim. That is obscene... I'm willing to bet that is a factor.

 

[randyknightjr]

you must have had a bad translator u didnt know how to use it properly. i love mine and most people i know that have them love them.

 

[v8s_are_slow]

I have no problems with mine. Works great. I may have to adjust the tune sometimes but it's just a click here and a click there. Nothing major. Running 7.7 in the 1/8th with only a maft and wideband for tuning ain't too bad...or at least I don't think so.

Also, if you're upgrading injectors, it definately helps to have a chip or something like Dsmlink to help with the tuning. Just throwing in bigger injectors and expecting it to run like it did on 450's is kind of a gamble. When I upgraded to my 1000cc injectors, I bought a chip before I threw them in and it definately made life easier. There's no way the ecu was gonna like that big of an injector with the stock chip. The Dsmchip definately makes life easier with all the bells and whistles as well such as stutterbox, etc.

 

[mattdev]

Hmm, I'll look into a possible faulty translator.

But as for DSM_PWR's subject- it isn't uncommon for people to have to set injector size 10-30cc larger/smaller. That was the moral of the story, I got carried away, haha.

DSMLink is on the way, the all powerful cash flow is the deciding factor.

 

[randyknightjr]

well i had o set mine for 720cc injectors for my 660cc injectors untill i figured out how it worked. now its set for 660's. runs great. it all depends on how much money you want to spend and how much power u are wanting to get, im not rich and i dont want an 700 horsepower car so my MAF-T is fine for me.

 

[v8s_are_slow]

Just checking, but are you guys doing okay now?

 

[echostats]

I believe I am having this same problem, but not completely sure. Is this what your problem is guys? Here's a video of what my car is doing.

Not only does the tach jump when parked, but while driving the car feels like it's hitting fuel cut at 5k RPM (10lbs boost). It shakes wildly. I have checked the fuel pressure and it's fine.

 

[randyknightjr]

i fixed my problem was fixed as described in this post, but i reringed my laser and i used a friends torque wrench and it was off by about 20 ft/lbs and i spun a rod bearing. but i almost have all my parts for a rebuild!