Miss at 6000 RPM
- Thread starter 1slow95
- Start date
I just changed the distributor and that didn't help. 
I got a fuel filter I'll put on tomorrow or sunday when I'm under the car working on the rear end. I doubt that will fix the problem, so what's next?
Could it be the computer or my chip gone bad? I was having problems with the car revving itself and shutting off randomly about the time this problem started. I cleaned the contacts on the chip and that helped for a while, then it came back, then it mysteriously went away.
I need to have this fixed by next friday for NMRA!!
Could it be the computer or my chip gone bad? I was having problems with the car revving itself and shutting off randomly about the time this problem started. I cleaned the contacts on the chip and that helped for a while, then it came back, then it mysteriously went away.
I need to have this fixed by next friday for NMRA!!
I tried to get a video of what it's doing, but it didn't turn out great.
http://www.mustangaddiction.com/movies/6kmiss.wmv
I think I'm going to order an adjustable FPR and fuel pressure gauge on monday. What gauge would I need to for the schrader valve on the fuel rail?
Edit: Will this work on our cars? http://store.summitracing.com/partd...=SUN-CP7818&N=700+4294839567+115&autoview=sku
http://www.mustangaddiction.com/movies/6kmiss.wmv
I think I'm going to order an adjustable FPR and fuel pressure gauge on monday. What gauge would I need to for the schrader valve on the fuel rail?
Edit: Will this work on our cars? http://store.summitracing.com/partd...=SUN-CP7818&N=700+4294839567+115&autoview=sku
I made some progress tonight. I installed the Aeromotive AFPR at 45psi(stock was 42), but that did almost nothing. So tried one more time unplugging my Crane ignition and using the stock ignition. Success!!....Almost. It still has a nasty pop/miss at 5800-6100, but it only does it 2-4 times and it's mostly smooth past 6k. Since this did not cure it completely, I'm thinking maybe my Crane box isn't bad...Is it possible the plugs/wires are at a point where they can mostly handle the stock current, but the extra voltage from the aftermarket box is too much?? My plugs are practically new, but I've had them out a couple times and dropped them several times. With how cheap a set of plugs are, I'm just going to pick up a new set tomorrow and try them out.
If it turns out to be the plug wires I will be pissed.
A $100 set of wires should last more than 6 months!
If it turns out to be the plug wires I will be pissed.
A $100 set of wires should last more than 6 months!
Redsnk95
Founding Member
Did you change the fuel filter yet? Sounds like a fuel problem. The crane box can go bad I had one that would work and not work intermintently.
Yep, changed the fuel filter.
IMO, the fact that it still does it when bypassing the crane ignition, even though it's not nearly as bad, tells me something is still wrong. Somebody mentioned once that a cracked spark plug would always miss at the same rpm every time, which is what it's doing. It used to be kind of intermittent, but lately it's been very consistent at just over 5800 rpm.
IMO, the fact that it still does it when bypassing the crane ignition, even though it's not nearly as bad, tells me something is still wrong. Somebody mentioned once that a cracked spark plug would always miss at the same rpm every time, which is what it's doing. It used to be kind of intermittent, but lately it's been very consistent at just over 5800 rpm.
94 Cobra 5.0
Member
Had a similar problem that you have been describing. On mine (stock for the most part) I had a above 4000 rpm. The cap rotor wires and plugs were just over a year old. Had bosch platinums in the car and kept having the misfire. Changed the bosch's out for champion plugs and a new stock coil and havent had a problem with it since. Dont know why it was having a problem with those plugs but my car doesnt like them. Might help might not hope you get this problem figured out. Matt
It's common for EFI 5.0s to not like platinum plugs. They don't conduct as well as copper plugs (but as a result, they last a long time with little gap erosion). The normal symptoms are the 4K RPM miss and sometimes a strange idle.
My car runs great at all rpm's until it hits 5800. Plus it used to run right with these plugs, it was very smooth up to 6300 or so when I let up.
I have a set of AR3924 plugs on order, they'll be in tomorrow.
Zero_chance
Founding Member
A kid that worked with me at my dealership had a similar problem and it turned out to be his fuel pump. Dont know how he diagnosed it but he said he replaced it and it went away. He stil ldrives the car and was doing passes in True Street at the Fun Ford weekend last week so it must be good.
Well now I feel like a complete idiot. When I first mentioned this problem on here(6-8 months ago), somebody mentioned it could be the crane box going bad. I thought for sure I tried bypassing it, and it didn't help...but that could have been for a different problem I was having. Tonight after I changed the spark plugs and found a plug wire that wasn't on all the way it was still doing it. So I unplugged the rev limiter and set it to "00"(so it's turned off). Unless it's a fluke thing, it went right up to 6200 like nothing.
So now I have a choice, live without a rev limiter or replace the ignition box. Does Crane have any kind of warranty?
So now I have a choice, live without a rev limiter or replace the ignition box. Does Crane have any kind of warranty?
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