Intermittant almost misfire feeling

[joshjwc9]

Recently since the rainstorms have started falling here in FL over the past week or so, i have been feeling a pretty steady misfire feeling only when my car is in cruise or at a steady speed it feels almost like a misfire like it is bogging and this feeling happens every few seconds or so. No check engine light and I have retarded the timing one degree in my predator too to play it safe.

I am going to give her a needed oil change tomorrow or the day after and I'm probably going to give the M1 Extended Performance a try.

Could it be the oil, or should I pull the plugs? Or could it be the fact that my exhaust is hanging a decent amount lower than normal and its path isn't as straight and level as could be?

 

[BLK$TANG]

pull the plugs

 

[squeak93]

Out of your ideas, the plugs are the only thing that will cause a misfire... Oil (unless blowing into the combustion chamber) will not, neither will low exhaust. Now an exhaust LEAK can cause major havoc on a mod motor.

 

[GDTrumbo]

OK. Delt with this problem on my daughters '00 Taurus just last week. Replacing the plugs is a good idea if you want, but there is one other thing it can be.

Pull one of the COP assemblies out. The lower 6 or 7 inches of the assembly is a long conical rubber tube with a spring inside. Over time this insulator (or boot) loses it's ability to do it's job. Kinda lika an old spark plug wire. This piece can be easily pulled off the coil and replaced.

They are available at O'Reilly's under the part # CP 035. This is a boot and spring for $3.19 each. Replace all of them.

I wonder how many people have replaced the whole COP ass'y at a cost of $77 each, when all they had to do was replace the boot ass'y!

GT

 

[joshjwc9]

I spoke with my mechanic, who is unable to look at the car until next week and said he believed either bad gas or something with the ignition is causing the problem. Friday, which is my next day off, I will pull the COP's and plugs to see if I can tell if there are any problems. I still have 3/4's of a tank so I will probably put some 93 in it next time I fill the tank (I have a 87 octane tune in the Diablo right now.)

I just kind of find it strange that at WOT it still feels as it should but at part throttle and set on CC it does not.

 

[GDTrumbo]

When I removed the COP assemblies, they "looked" alright. Soft, plyable, didn't seem to be possible that there was a problem. I even tried cleaning them up to no avail. Only thing I could figure was maybe they were carbon tracking.

The car even starts up with more vigor now.

GT

 

[84Ttop]

had the exact same problems w/ my 98 GT. The 02 sensors were bad and not allowing the car to go into a closed loop. I ran great wide open but did the same thing at part throttle. No check engine light on mine either.

 

[joshjwc9]

Watching my predator the car stays in closed loop pretty much at all points of driving except for slow shifting into 2nd and 3rd the car stays in closed loop.

But in watching my predator, under the TPS sensor monitoring (I think) the car whenever I am on the throttle it says WOT, then when I let off it comes up with a "?".

The thing that burns me is the fact that it still feels as though all of the power is there at WOT. But normal driving it seems as though it is slightly hiccuping.

A friend who used to be a mechanic before he got an injury told me that he believes that the thermostat is opening too early, causing the car to go into closed loop too early. Could that be possible to be the issue?

I am probably just going to wait until next week and have my mechanic look at it, since this is driving me nuts and I know he will get it right.

 

[trombonedemon]

Hey man, replace all of your spark plugs, get decent gas, sounds like you car just needs a tune up, nothing to be worried about, if at all, if your thermostat is opening too early, than your car temp monitor would read it. Seems like a simple fix.

 

[joshjwc9]

I like your optimism, but I am a pessimist if my car isn't running right, and I just had new plugs put in not too long ago.

 

[squeak93]

So your tps isn't registering at the puter? If thats what you mean by the predator giving your a "?".... Check the votage manually at the tps and get back with us.

 

[joshjwc9]

IDK what it means, when I let off the throttle and no cruise is engaged that is what comes up. IDK if something else is supposed to show up or not. I just figured someone who has more knowledge than I do with Diablo Predators would know.

 

[BLK$TANG]

I had the same problem last week, the previous owner changed the thermostat and put the seal under it (smh dumbass). Antfreeze started leaking out and ended up in the plug wells, there was puddles of it. I dried out the wells the best i could and changed the plugs now car runs like a champ.

 

[joshjwc9]

Plugs are dry, I pulled the COPS but I will not touch my plugs (don't want to strip out a helicoil that is in one of the plug holes).

This is because the car just shot a p0302 Cylinder 2 Misfire Detected. I switched out COPS and added a new one to Cylinder 2 (second in from the front on Pass. side) and Cylinder 5 (first from the front on drivers side) in case I messed up my cylinder numbering with me being pissed off.

My mechanic said earlier this week because it isn't throwing codes it could be the EGR since it is at part throttle and I disconnected it without any help.

And now I gave him a call today and he thinks it could be within the injector, the helicoil itself or in the computer screwing with the tune.

So on Mon. or Tues. the car is going back to him to pull the plug, double check it, redo the helicoil and if need be to put a new injector in that cylinder.

One quick question, will a stock 19lb injector off a '95 GT fit my stock injector harness? This is just to check it instead of switching injectors with another cylinder to see if the code follows the injector...