Stumbling in high rpms...only at WOT
10-30-2006, 04:24 PM
#1
Stumbling in high rpms...only at WOT To start things off my car only has 62k on it. I know that doesn't mean things cant go wrong but I wasn't prepared for them to start.
Anyway, lately my car has been cutting out at high rpms when going WOT. It wont do it every time, but when it does it, it makes a loud pop out of my cutout. Also when in neutral and I rev it up by going WOT it will cut out a few times when the rpms get a little past 4k. It usually does this every time. If I bring the rpms up without going WOT the car runs fine. What would cause it to do it only under WOT? Everything else is fine too, the car idles fine, drives fine in all other conditions, only at WOT in the upper rpms am I noticing this problem. Thanks for your help.
Andy
Anyway, lately my car has been cutting out at high rpms when going WOT. It wont do it every time, but when it does it, it makes a loud pop out of my cutout. Also when in neutral and I rev it up by going WOT it will cut out a few times when the rpms get a little past 4k. It usually does this every time. If I bring the rpms up without going WOT the car runs fine. What would cause it to do it only under WOT? Everything else is fine too, the car idles fine, drives fine in all other conditions, only at WOT in the upper rpms am I noticing this problem. Thanks for your help.
Andy
10-30-2006, 07:55 PM
#5
The crappy part is I have hardly any knowledge on how to check anything myself. I don't know what the hell I'm gonna do if something needs to be replaced. If I can't figure it out myself it looks like shes going to sleep through the winter sick.
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11-01-2006, 09:56 PM
#8
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My LT1 is doing the same thing . It idles fine,drives ok up until about 3000-3500 rpms and everything just goes to ****.It starts backfireing and no power but it's trying. I've replaced everything. MAF Opti disrtributor plugs wires,Fuel pump. No Codes. It keeps going in and out of Open and closed loop mode. Plugs are wet. i replaced the coil. WTF! It's gona drive me insane. Mayby O2's? But Scanner show they are working properly. Idle went up about 200rpms too.
11-01-2006, 11:41 PM
#11
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Mine was doing the same thing when I bought it. I had all types of fears of problems that ranged from bad opti to bad fuel pump.
I was told that the car had a recent tune-up. However, I found a box in the hatch that had the new plug wires and TWO new plugs, which told me that two of them weren't changed.
I decided to take on the dreaded tune up job myself. My findings were: (1)the two plugs that were not changed had verry little electrodes left on them, (2) at least one plug boot was not secured properly, and (3) the other 6 plugs that were changed were gapped incorrectly. The LT1s require a 0.050" gap. The plugs that were installed were 0.040". It was a wonder how the damn car even ran at all! However, it runs like a champ now after new plugs and wires.
I was told that the car had a recent tune-up. However, I found a box in the hatch that had the new plug wires and TWO new plugs, which told me that two of them weren't changed.
I decided to take on the dreaded tune up job myself. My findings were: (1)the two plugs that were not changed had verry little electrodes left on them, (2) at least one plug boot was not secured properly, and (3) the other 6 plugs that were changed were gapped incorrectly. The LT1s require a 0.050" gap. The plugs that were installed were 0.040". It was a wonder how the damn car even ran at all! However, it runs like a champ now after new plugs and wires.
11-01-2006, 11:47 PM
#12
Originally Posted by bmealer
The LT1s require a 0.050" gap. The plugs that were installed were 0.040". It was a wonder how the damn car even ran at all!
Don't see how an .040 gap is any worse.
11-02-2006, 12:10 AM
#14
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Well, the "It was a wonder how the damn car even ran at all!" was referring to all 3 issues combined. However, as much as changing plugs were a PITA, I wasn't gonna risk trying a different gap only to find out it didn't run well. I sure didn't want to do it twice!!! 
11-02-2006, 01:23 AM
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Alright guys. We all love our Mustang Killers so lets put our heads together and solve this problem. Car runs great up until 3000-3500....... what could cause this besides Opti distributor. I just put a new one on and it started doing it not even 5 minutes after the install. New plugs and new wires. New MAF, New feul pump, New coil pack MSD. No codes..... O2's mayby? RPM's are up by 250rpms out of no where.
11-02-2006, 09:42 PM
#16
I was told to change the coil and see if that works. Someone on another forum said he only had 50k on his car and it was doing the same thing. His coil was pretty rusty he said and he changed it with an MSD blaster and it runs fine now. I also heard to check the opti to make sure any screws on the cap and rotor didn't back out. The weird thing with mine is that it wont do it all the time and going WOT, and with WOT revs it pops when it gets a little over 4k and it will do it a couple of times all the way to 5500 and it does this every time. The thing runs completely fine and normal in any other circumstances. Does my problem sound more like a fuel or ignition problem. Or is it just too hard to tell? Thanks for everyones help too.
11-02-2006, 11:39 PM
#17
I sure am having a hard time figuring out this problem. Do you have aftermarket rockerarms? I have been through everything but that. I am Gonna double check my wires again and then my ignition control module. Would that set a code if it was going out? Someone else told me to check the wireing harness leading to the optispark. They said it could get corroded. I really need to check the fuel problem as well but it just started doing after I installed my fuel pump. walbro 255. It's got to be an ignition problem though. I have a brand new MSD Blastercoil + Opti distributor +plugs and Wires fuel pump.
11-19-2006, 12:53 PM
#20
i hate to add to the problem but mine does it too. I plan on changing the pump to make sure it's not a fueling problem. I may buy a Fuel Pressure Guage and see what my psi. is. I've already changed plugs and wires, fuel filter and air filter. I'm thinking it's the opti. I have 80k on my car and as far as i know it's never been changed. If i don't have bad fuel pressure i'll look into getting an opti instead of a fuel pump. we'll see how all this goes as winter proceed's. As for not doing work yourself. Buy a Haynes book or see if you can get the GM service disk's from somebody. Once you start to dig in just remember, don't loose parts, clean surfaces, and double and triple check everything before you put it all back together. 3 things to remember when working on motor's.~Cole~
