Free diagnostic test that I'll bet will help a lot. Pull your plugs, narrow the gap, put them back in and go for a drive to see if it improves. I bet it does.

 

hey bruteford thanks for the input it does make sense I never checked the gap there brand new plugs I just assumed they were set to spec im just wondering if uv seen this concern before

 

Yup had a few vehicles I've worked on act that way. It happens cause the coil gets weaker as RPM goes up and at a certain point can no longer jump the plug gap. If that solves/helps the issue then it's time to talk ignition upgrades. I have recommendations I make but better to try this free fix before tossing money at it.

 

well I will pull the plugs and check the gap tomorrow after work and let you no what happens thanks a bunch

 

so I just got back from my rd test narrowing the gap did not help I checked the gap on each plug they were set to spec at just over .40 I set them all to .30 checked for cracks and or poor condition they all appear fine time to dig deeper I guess

 

Would it be possible for it to lose cylinder compression at 3500 rpm? It doesn't seem like it but otherwise I don't know what to suggest.

 

I wouldn't think so but to tell you the truth im lost on this one iv never been this lost don't get me wrong Iv had brain teasers before on a day to day basis but never anything like this and to make it worse its my own personal rig the thing that gets me is it runs so good till it hits that point in the rpms then it pretty much falls on its face it acts like a combo of it hitting a rev limiter witch it don't have or like the distributer has gotten wet very frustrating but I cant give up I don't have it in me

 

OK I'm stumped and that doesn't happen often. Let's start here, when did it start, what was done before it started and how long have you owned it.

Like for example if you've had it for a while, it's never had this problem before but started after a tune up.

 

I got it last winter it was in stock form and to be honest a big pos but I liked it through the winter I lifted it went through everything from front to rear brakes ball joints everything the poor thing had been neglected its whole life but it only had 140.000 on it and ran like a top I never drove it except in the parking lot at my shop cause the e40nono was on its way out after searching and searching I finally found my t18 4spd parts truck I transplanted the t18 in it and finished up a few other odds and ends so it was ready enough for the trails I took it out a few times and it went awesome no complaints what so ever then one day me and a buddy about 2 months ago or so were headed out for a ride and it started to run like crap in the higher rpms so I said ok im sure it needs a tune up prob never been done so that's when I changed the plugs wires cap and rotor then it was fine took it out many times after that and it went great the plugs were in very bad shape aswell as the cap and rotor I took it to work one day id say prob three wks or a month ago and it started doing it again but a lot worse and now im just throwing parts at it I hate to do that but I don't no what else to do cause like I said its a very hard concern to dg as I have no codes to work with

 

So that running like crap at higher rpms 2 months ago, is that the exact same issue it has now and if not how has it changed and when?

 

it was pretty much the same just not as bad like now i can hold it rite at 3500 rpms when it does it and it will just sit rite there and flutter like its hitting the rev limiter and it wont power out of it the only way it will stop is if i back out of it but as soon as i get it back up to 3500 it starts rite up again worse in 2nd gear in 3rd it will buck and jerk around

 

Things like this are very often ignition related. One trick I do that might work for you to tell you more about what's going on is to use a timing light as a spark indicator. Inductive timing lights(the clamp on the wire) only flash when current flows through the wire and current only flows through the wire when it sparks. So I'll hook up the timing light on the coil wire, tape the button down and watch it while revving or driving. So if it stops sparking you'll see the timing light stop flashing, if it's flashing too fast and you can't notice try a plug wire.

 

ok my timing light is at work ill try that tomorrow thanks for the input I will be sure to let you no what I come up with thanks again

 

check the cap for cracks, Have you unbolted the Y pipe to make sure the cat converter isnt clogged, i have seen where it will hold the engine back when hitting the higher rpms.
also make sure that plug wires 7 & 8 are not touching at all as they are prone to arc/missfire. are you running the stock coil or an aftermarket coil? the plug gap should be .44-.45 and should be a copper plug, dont run that expensive crap in there.

 

hey kemicalburns the plugs wires cap and rotor are all brand new as of two months ago just last week I put another set of wires and another cap and rotor all parts are factory motorcraft lastnite I put another coil in it a brand new motorcraft one today I reset the gap back to factory spec .45 I just went out and checked the wires they are all in the supplied holders no wires are touching one another I also did the timing light test recommended by bruteford maybe I was doing it wrong but I never saw the flashing stop when the concern was present this thing is driving me crazy thank you for your input any other suggestions would be great