Misses when it starts

[matts95]

Ok guys, my 2000 mustang gt has a missing and running rough issue when it is first started after it has sat there for a while. I can't even give it gas or it will die. After about 15 seconds it clears up. It also idles up and down when im at a stop. What could be causing these issues?????

[Blackout]

idle air control valve could be going bad and/or have water around the spark plugs. could also be a vacuum leak somewhere, your mass air could also be bad. There are multiple things that could be the reasons. need more information.

[plated]

cop's

[03z06vette]

Pulll the vacume line off of the fuel regulator and see if it smell like gas. mabie a pin hole in the diaphragm.

[Blackout]

is the car throwing codes?

[matts95]

No codes at all. I have a diablo tuner and nothing comes up. I cleaned the idle air control valve and the mass air meter. I changed the plugs this past weekend with motorsport plugs and gaped at .054. No change with the new plugs and everything cleaned. I turned up the idle to 755 rpm to see if it helps the irratic idle. So far no real change. It also pops pretty good when i let off the throttle above 2500 rpm. I can't find any vaccum leaks.

[Blackout]

OK So the car sets over night, it will miss at idle in the morning. It could possibly be the COP's. But it sounds from what you telling us is that when the car warms up it runs fine. Does the car smoke or anything?

I do know if the Mass/Air is messed up it will not run well at all. And if you press the gas pedel it will cut out. Also the Throttle position sensor could also give you the same symptoms. When the car is cold and acting up, start unplugging the mass air and other components that will have an impact on the way the car runs when cold. Also you can unplug one cop at a time and see if changes also.

[03z06vette]

Does it back fire at all when you try to give it gas or just stall.

[matts95]

Well yesterday i was driving home from work and the car started lunging. It has done this a few times the past week. This time i got a check engine light. I hooked up the tuner and checked the codes. It said something about fuel pump driver disabled....That confused me because if it was disabled wouldn't the car die? So, the car doesn't want to run when first started. Misses and if i touch the gas it dies. It will idle up and run ok. Now i have the idle set to 755 and the car never goes below 1100. When i come to a stop sign or light it revs to 1400 then idles down to about 1100. It holds there steady. So i checked the tps. It was about 0.96v so i didn't change it. I cleaned the mass air and the idle air control valve. wtf can it be??????

[cobra429boss]

fuel pump may be going bad.. find you a fuel gauge hook it up and see if its losing fuel pressure when you rev on it

[blown96cobra]

2x on the fuel pump. my 02 did the same thing, i bought a bbk pump changed it out and it ran perfect you may want to check your fuel filter first it could be clogged and causing everything to freak out.

[matts95]

ok well i repalced the fuel filter and put a ford gt pump on. Now it has a slight miss below 1200 rpm. If i let off the gas while i am driving it lunges. What the fu$$ is going on. No codes at all. I am about to take it to dayton performance and see what he says. Any other ideas would be helpful.oh ya and the starting problem is still there.................

[bobtsgt]

did you have a change in the tune before these problems started up? datalogging some parameters would help point you in the right way. Or at least show you whats working and whats not

[blown96cobra]

start unplugging the cops one by one. If nothing changes when you unplug one theres you issue. I doubt thats it but ive seen them cause some weird shit to happen.

[JIMS SVT]

Had a 02 sensor do this to me before.

[matts95]

It has a pypes catless intermediate pipe. I put the factory tune back in and its doing the same thing. I will try datalogging today sometime. I have never done it but I am able to on the predator.

[JIMS SVT]

I had a off road x pipe when my 02 was bad.

[91boost]

I would check cops

[matts95]

So if it had a bad 02 would it throw a code? Ill check the cops tonight. I guess unplug each one and try to hear if it changes or not

[blown96cobra]

try to do it at night pull each one plugged in and it start the car there should be a bright blue spark coming out of each one about an inch. if you have a diablo is should tell you which cylinders are misfiring. thats how i traced mine down, also look for water or antifreeze in the plug holes. Honestly the best thing to do is just suck it up and buy a whole set of cops, you can get accels for about 120 on ebay, usually once one goes bad there rest are soon to follow.

[Blackout]

Did you ever figure out the problem?

[motox159]

what's the cop's? coil packs? just curious....

[matts95]

I had my cousins wedding Saturday and we took the kids to youngs to get pumpkins yesterday so I didn't have time to work on it. I'm going to try to look at it tonight and see what I can find. Cops means coil on plugs. Would a cop cause it to not want to start in the morning? I reloaded the factory tune on Friday to try to get a code and so far nothing

[blown96cobra]

i just tore my spare parts bin apart lookin for some xtra cops, i had about 5 good ones when i did the msd swap but my wife must have thrown them away i was gonna mail them to you. let me know if you get it figured out if nothing else next time im around cinci i can check it out at see whats goin on with it.

[bobtsgt]

pull the plugs and see what they look like. also if you turn the key back and forth a couple of times before starting it does it start quicker or the same?

[matts95]

Ok well I have a boot on one of the

[matts95]

I hit submit on accident. Lol I have a cop that has a rip in the boot so I am going to replace that tonight hopefully. I drove it tonight for about 10 minutes and the thing started missing so bad it would barely run. I romped on it a couple times and it smoothed out for a minute and started to miss bad again. I got home and checked the codes and I got a P0352 which is a ignition coil b primary/secondary circuit. I don't know what that is. Also a P0136 02 circuit bank 1, sensor 2 and P0141 02 heater circuit bank 1,sensor 2. So I think I need a oxygen sensor but I don't know what side bank 1 is. I assume that sensor 2 is after the cats...right?

[Blackout]

I think that that I just had the same thing happen to me exept mine was "E". It's the number 2 cylinder. Your C.O.P is screwed. I just replaced one of mine and it fixed the problem. I still have a few of them left if your still interested. We can at least try them, go down the road and if it fixes it, buy them. If not..no harm no foul. But at least you will be able to rule some stuff out. Plus I will be able to take a look at it.

[matts95]

I replaced the boot on the #2 cylinder and it ran perfect. So I put the tune back on and it started the same bs again only not as bad. Can it be a 02 sensor also. It got worse as it got heated up. And I will still be getting a cop from you blackout. I've just had a crappy week with me falling off the roof and then my 5 year old has strep now. Ill get by there this week sometime, maybe Monday would work. Ill let you know. Thanks for all the help....

[blown96cobra]

an o2 sensor should only cause an issue when its in closed loop, sounds like a bad cop id replace them all with new ones. summit or jegs has them cheap. if that doesnt do it look for a cracked vac hose comming off the back of the plenum that rots quick and ive seen it cause ur types of issues. get some propane and check for vac leaks or bring. bonehead move on mypart i just read your post again and if it runs fine on your stock tune either the ecu is acting weird or the tuner is junk. its the custom with modified parameters or just the stock 93 tune? If your ever get anywhere near chilli on a fri or sunday id be more than happy to help you troubleshoot it with you. ive had alot of the same problems your describing.

[matts95]

Ok after a few hours at blackout's house and changing everything I think its fixed...We swapped all the cops and no real change. We swapped the idle air control valve and no change. Unplugged all injectors one at a time and it missed like it should. Finally we changed the tps and it ran awesome. It missed for about a half mile after I left his house but it smoothed out before I got on the highway.. It ran flawlessly on the highway, even when I let off of the gas it didn't buck or miss at all. I just wanted to let everyone know what it was. I really want to thank blackout for all his help tonight. He is awesome with the mod motors. Anyone need help just ask blackout. Thanks again allan, ill call you tomorrow and let you know how it does on the way to work.

[Blackout]

Glad to help another banger out. Sorry in getting you in trouble with your other half.:) Yeah let me know how your car does. I think that the computer just had to read the new values of the TPS and correct your fuel values. These cars are simple and only a handful of things can be wrong. Good meeting you man, (even though we worked together @ DMAX and didn't know it...lol) and glad it worked. I will text you tomorrow to check on the car.

[blown96cobra]

glad you got it fixed 2vs can be a mother, thats why i went back to pushrod motors lol.