Car bucking/stumbling/hesitating/misfiring

[randol35]

On a cold start and drive the car is bucking, stumbling, hesitating, and misfiring. I thought it could be bad spark plugs but I replaced them today and still the same thing. When fully warmed up, I still get the exact same symptoms, just not as severe. Under WOT when fully warmed up I can barely tell anything different is happening. This started randomly the other day when I started it up and drove away and felt the problem. Its kind of getting worse everytime I cold start and drive. At idle a misfire is clearly heard and is persistent.

Just put in brand new bpr7's and I have a COP setup. No check engine light.

 

[ADrewzki]

Unplugged MAS? Blown IC hose? I'm not familiar with a COP setup. Is it still possible to have wires switched?

Just out of curiosity, is there a reason you want with the BPR7s instead of the 6s? High boost car? Stock? I can't tell since your profile isn't filled out *hint hint*

 

[randol35]

I went with BPR7s because I have a 16g and when I install my injectors safc and 255 pump I will be at 20 lbs.

 

[4g63eagle]

I had the same problem, It was the c.o.p setup. Your plate could have the black&silver trigger wire's in the wrong polarity,but my problem was i didnt have a c.d.i

 

[xhackerekx]

set plug to 0.28

 

[randol35]

I had the same problem, It was the c.o.p setup. Your plate could have the black&silver trigger wire's in the wrong polarity,but my problem was i didnt have a c.d.i

Was it a gradual problem or did it randomly happen?

 

[randol35]

I just got a logger today and checked the car out, just wondering what I should look for on the logger that could lead me towards my problem?

 

[ballersixty9]

is there any lioght on this happened to me and it was the ecu the caps started leaking.

 

[randol35]

Nope no CEL. I checked for codes stored and there werent any.

 

[DSMDriver69]

have you checked plugs and plug wires. i had miss fire issues yesterday and I replaced both. It partially fixed the problem, and then i found out my turbo had horribile shaft play. Did you just use a hand held scanner to read fault codes?

 

[PieEyedPiper]

I vote possible ECU and even more possible COP. What kiind is it? Do you have a CDI?

 

[randol35]

have you checked plugs and plug wires. i had miss fire issues yesterday and I replaced both. It partially fixed the problem, and then i found out my turbo had horribile shaft play. Did you just use a hand held scanner to read fault codes?

I have COP. I changed the plugs after the problem started since I thought that was the problem.


How could the ECU be the problem? The symptoms change due to temperature, so I dont know how the ECU could be causing any of this.

Did you just use a hand held scanner to read fault codes?

Yes a Palm Datalogger with MMCD.

Another problem that has consistently gotten worse with this problem is when I turn the key to start the car, I have to hold the key it there for about 3 seconds until the motor turns over. Sometimes when the motor is fully warmed up and I go to start the car again I turn the key and nothing happens at all, and I have to take the key out, put it back in and try it again, and after about 3-5 seconds of holding the key there it will turn over and start.

Could this be related to my problem?

 

[randol35]

Update, car is still running like complete shit

150 compression across the board

Thought plugs needed to be changed, now brand new NGK BPR7es @ .28, didn't help.

Thought COP sucked, replaced with stock ignition, nothing.

Looked at my ECU, had a tiny bit of leakage but nothing crazy, swapped ECU's, didnt help.

Mechanical Timing is good.

No codes.

Unplugging MAF doesn't change anything.

Replaced ignition Transistor, nothing changed.

Realized CAS was fully advancing timing, did timing, nothing different.

When warmed up the car kinda decently pulls through 1st gear when I punch it at 4k rpm, but when I hit second gear, the car just soundes like its choking.

Also the plugs look very lean so its gotta be a fuel problem...?

I did a log with the car fully warmed up through 1st gear and 2nd gear until 4k rpms and at 3k-5k rpm in first gear I had 42 counts of knock the whole time.

 

[Fabian]

unplugging your MAS and it running the same should be the slap in the face you need dude. I'd replace that and I'm willing to bet your problem will go away

 

[randol35]

unplugging your MAS and it running the same should be the slap in the face you need dude. I'd replace that and I'm willing to bet your problem will go away

It doesnt run the same, when I unplug the MAF i get tons of idle surge, and the car hesitates about 5 times more.

 

[PieEyedPiper]

And how did your BLT go?

 

[randol35]

And how did your BLT go?

didnt do one yet I need to borrow someones compressor

 

[PieEyedPiper]

No need for a compressor. This is likely the first thing that you should have checked. but you can get on-board with a bike pump but I wouldn't waste my time. Go buy an electric air pump/compressor from ACE for $9. Mine works wonderfully and will operate upwards of 60psi..maybe even 90? I don't recall.

p.s.
watch out for capitalization and punctuation, etc.

 

[randol35]

I changed the fuel filter and it did clean up the idle a lot, even though the misfire is still faintly heard at idle. Fully warmed up, after about 3 WOT pulls the car seems to feel alright, but at low RPM with a lot of load on the motor, it still chugs and bucks. Im not sure what to move onto next, maybe use some Seafoam to clean out the fuel system, or checking/replacing injectors and pump. I have 560's and a 255, but not sure if I should install them yet to see if it was the pump/injectors causing the problem.

 

[shockracer]

any updates on this, im getting almost the same thing and im all stock?

just put in a new fuel filter, new plug wires (ngk's), plugs are almost new and still look good.
still getting the bucking and a little hesitation, i just ordered a new coil pack for $101, from advanced auto parts.
I hope that the coil pack will solve my problem since this is my DD.

 

[shockracer]

update: my problem is fixed for now, tried gapping at .028 ran horrible, then tried .032 and she loves it. still a slight miss at idle every now and then but she pulls harder then ever.

 

[sek_phok]

try setting the plugs to .28

 

[Gasolinebaptism]

Randol35. I just read through your thread. and to be honest I somehow knew right away that it was fuel. I've felt this kind of thing w/ dirtbikes. but whether it's the pump or injectors i'm not sure.
I would say pump. but it could be many things. pump is the first thing i would change.
Other possibilities, are a burnt pump, because of low voltage, meaning weak alternator or battery. (test them)
A jacked up ecu sending FUBAR signal to injectors.

I really want to say it's your pump though man.