Seems like fuel cut, but at part throttle with no boost

[Skip01]

Ok, well I searched a bunch of part throttle threads but none seemed to do what mine is I believe

I noticed it this morning, if I go over 3000ish rpm, part throttle or full throttle it seems like my car hits fuel cut, or that it just doesn't get fuel and stops accelerating no matter what amount of throttle I give it , it would buck badly off and on

I figured out that if I keep it around 2k too shift I could keep driving, so I did that and on way to work hit some traffic which held me up for about 15min with car running
Then once it cleared it boosted fine past 3k when I tested it. Pulled in 3rd and 4th gear and was fine 10psi at 3000 and 15ish at 3500 no signs of bucking

Now we all know problems that just go away on their own are no good, so any thoughts?

No I haven't done a boost leak test yet, I know that's everyones first suspect , ill try that Sat perhaps

 

[JayRolla]

Yes BLT. Sounds like it was cold in the morning and the air is denser which will cause fuel cuts or spark breakup due too a boost leak.

 

[Skip01]

I got my Pocketlogger working a few min ago and got these codes

11: 02 Sensor
12: Airflow sensor
41: Injector Circuit

I know I see a 02 sensor unplugged by my wastegate dump, and is Code 12 my MAF?

And I can hit fuel cut even when I don't go into boost?

Thanks for reply

 

[JayRolla]

Your car is stuck in open loop, get that o2 plugged in. Airflow sensor I think is the maf and could be your problem. Go to the junkyard or find a replacement maf. Not sure what the injector circuit is but that sounds like it may be an issue also. If the injectors are having problems thats never good. Could be a failing injector, or bad maf. The o2 is just giving you bad gas mileage.

 

[Skip01]

Your car is stuck in open loop, get that o2 plugged in. Airflow sensor I think is the maf and could be your problem. Go to the junkyard or find a replacement maf. Not sure what the injector circuit is but that sounds like it may be an issue also. If the injectors are having problems thats never good. Could be a failing injector, or bad maf. The o2 is just giving you bad gas mileage.

Ima take pics of the O2, ### i have no idea where it plugs into

And i tested my injectors 1 by one with my pocketlogger and they all seem to be in working order

Ill try to get a log this week

Thanks for the help

And i have a 2g maf waiting to go in, but i wanted to get bigger injectors first...ill see though

 

[Skip01]

Ok well a update:

I've still not been able to do a boost leak test, as my tester was too big for the coupler I bought.

But I said, welp , let me go head and change my MAF to the 2g maf while I got it since I had a air sensor code anyways

I did that just a lil while ago and everything seems back to normal and than some. With a few 1st gear pulls at my work on a dusty road it spooled up fine and spun all 4 tires, which it never did before when I tried.

Ill make some 3rd gear pulls and try to get a log of it.

But no hesistation or cut or buck or anything so far

 

[andy4g63]

Check exactly, what your battery voltage is. I had a kind of similar problem andit was my battery was dying/wasn't holding enough charge/. Good battery should be at least 12.5 and above.

 

[Skip01]

Check exactly, what your battery voltage is. I had a kind of similar problem andit was my battery was dying/wasn't holding enough charge/. Good battery should be at least 12.5 and above.

Yehhh runnin its 14.1ish

It seems good

Like i said the problem seems to have been fixed with the new maf, but im gonna try a boost leak test next week i think if i can find a coupler to fit

Thanks again for the help

 

[Skip01]

Ohhh....does anyone know if the 2g maf is supposed to have a lil pipe coming out the the recirculation tube like the 1g does?

Right now i just have my tube just snuggly stuck in the opening.....whereas the 1g recir. part had a lil pipe stuck in there and my tube stuck over that pipe...

Any thoughts?

 

[andy4g63]

I meant , check the battery, with the motor not running. Even with motor running and voltage around 14.1-14.2V, doesn't mean at all that battery is good. Leave it overnight and test it with volmeter next day. Batterythat is bellow 12V is considered dead, at 12V battery is considered 25% charged, at 12.35V is 50% charged, etc, So do that and if it is not good buy new one. If you don't want, let it charge good and slow-like 6-8 hours and drive it right after that , see if it still does breaks up and buckle.

You'd be surprised how people underestimate the battery.

 

[Colt4G63 also]

I can't believe your O2 sensor is unplugged and you are saying everything seems fine now. Wanna' race for pinks?

 

[Dragon TalonTsi]

Those codes only meant that the specific circuit has to be checked out. It doesn't mean your components are bad, but the wiring to it, the connectors, or the entire circuit itself has to be looked at. It could have an electrical fault that you don't know how to fix, so just swapping parts IS NOT going to fix it. Those 2 are the major input sensors where as the fuel injection is the output. Without the other 2 working (especially the MAF) your car will do exactly what its supposed do, run like crap. The MAF tells the PCM how much incoming air is reaching so it can adjust the fuel trims accordingly, where as the 02 sensor and ECT both cause the PCM to do the same, and cause the PCM to come out of open loop and merge to closed loop. And your fuel injectors, well, that's for fuel... And I suspect there is a high/low resistance fault, but not for sure. You said when its cold it does that, and temperature effects resistance. I wouldn't just throw parts at it first until you figure out the reason the codes came on in the first place.

 

[Skip01]

I can't believe your O2 sensor is unplugged and you are saying everything seems fine now. Wanna' race for pinks?

I believe it was a O2 sensor added to tune with WideBand.....nothing that was stock

Like i said its on the wastegate dump portion

And i dont see where it would plug into....i keep forgetting to take pics but ill do so later


And andy.....it doesnt breakup anymore since i changed the MAF

 

[Dragon TalonTsi]

You'd be surprised how people underestimate the battery.

You said it right bud. I just had 3 customers yesterday with a "bad" battery. They didn't listen as to how the automotive battery takes the most abuse under the hood. I mean, with a water/sulfuric acid concentration for the batteries ultimate power source, its going to expand and contract internally several hundred times. And in the winter days, it shows its weaknesses of broken cells and low solution concentrations.

You were on the right track, 12.2 and below is <25%, 12.3 is about 25%, 12.4 is 50%, 12.5 is 75% and 12.6 is 100%

I would tell the specific gravity results, but that's another detailed post...

 

[Skip01]

Those codes only meant that the specific circuit has to be checked out. It doesn't mean your components are bad, but the wiring to it, the connectors, or the entire circuit itself has to be looked at. It could have an electrical fault that you don't know how to fix, so just swapping parts IS NOT going to fix it. Those 2 are the major input sensors where as the fuel injection is the output. Without the other 2 working (especially the MAF) your car will do exactly what its supposed do, run like crap. The MAF tells the PCM how much incoming air is reaching so it can adjust the fuel trims accordingly, where as the 02 sensor and ECT both cause the PCM to do the same, and cause the PCM to come out of open loop and merge to closed loop. And your fuel injectors, well, that's for fuel... And I suspect there is a high/low resistance fault, but not for sure. You said when its cold it does that, and temperature effects resistance. I wouldn't just throw parts at it first until you figure out the reason the codes came on in the first place.

Well I got the codes when i checked with my pocketlogger...its always had a CEL but ran fine

So check the wiring to the wiring harness and such, what should i look for?

Burnt wires, or open/ exposed ones?

 

[Dragon TalonTsi]

I believe it was a O2 sensor added to tune with WideBand.....nothing that was stock

Like i said its on the wastegate dump portion

And i dont see where it would plug into....i keep forgetting to take pics but ill do so later


And andy.....it doesnt breakup anymore since i changed the MAF

So it could've been the MAF, but at the same time, it would've been nice to see the full diagnosis of what went bad. Throwing parts is not the way to go, even if you have millions of dollars to spend.

 

[Skip01]

So it could've been the MAF, but at the same time, it would've been nice to see the full diagnosis of what went bad. Throwing parts is not the way to go, even if you have millions of dollars to spend.

Yehh, i understand....i mean if i knew more about DSMs i ###### coulda done more beforehand

But i was gonna change to a 2g MAF anyways so i thought welp, let me put this on and see what happens


Theres like 2 other plugs that are just unplugged as well....on pass side by the front.....one big one with like a small pointy tube on the end, and another smaller one thats on the same harness as the MAF plug

 

[Dragon TalonTsi]

Well I got the codes when i checked with my pocketlogger...its always had a CEL but ran fine

So check the wiring to the wiring harness and such, what should i look for?

Burnt wires, or open/ exposed ones?

The CEL/MIL/SES etc. light is all the same. That comes on for a reason, its not there just for fun. You think it ran fine, but something was wrong. And it doesn't mean that everytime it comes on something is in dire need, it just means you have a fault. I had this problem before, it would only come on at WOT use, found out it was my IAC and TPS, but only at those specified conditions, it would act up. It would then go away after I get off the throttle and am not under boost.

Yeah, you wanna check for opens, shorts (to either ground or power) and resistance problems (i.e. loose, dirty, open grounds). This isn't something you can just rip apart, there is foot after foot of wires, so be careful, make sure you have a schematic and the proper tools to fix them, and go to town. Make sure you unplug the battery and take all precautions before working on any electrical system.

 

[Dragon TalonTsi]

Yehh, i understand....i mean if i knew more about DSMs i ###### coulda done more beforehand

But i was gonna change to a 2g MAF anyways so i thought welp, let me put this on and see what happens


Theres like 2 other plugs that are just unplugged as well....on pass side by the front.....one big one with like a small pointy tube on the end, and another smaller one thats on the same harness as the MAF plug

Without pics, its not going to help out. And its not just knowing more about DSM's, its a basic concept for all automobiles. Its not like DSM's use a special battery made with kryptonite and sawdust, its the same basics throughout.

And it could still be very well affecting your MAF status. It might not work just swapping parts, but you wanna do it, so give it a try.

 

[Skip01]

I have a vid coming shortly, showing the plugs that are unplugged and the o2 sensor

 

[kicker91laser]

Fwiw, my 91 laser did this in the past, but it would never clear up even after it was warmed up. I swapped out the ecu an the problem never came back. The ecu also looked fine visually, no leaking caps or anything.

 

[Skip01]

Fwiw, my 91 laser did this in the past, but it would never clear up even after it was warmed up. I swapped out the ecu an the problem never came back. The ecu also looked fine visually, no leaking caps or anything.

Well i havent actually drove it yet more than a 1st gear full throttle pull but it didnt do it after i changed to the 2g maf.

Before it would do it constantly in 1st gear no matter if i went 100% or part throttle

If it does it again ill look into changing the ECU

 

[Skip01]

Ok heres the vid......yep, my fingers are fat:

You must be logged in to view this image or video.