High rpm miss

[unluckyty]

The Shadow has developed a problem, I am unable to figure out. Car is 87 es converted to tII, 255 ,+40's,afpr, 3bar map/ 3bar chip, t3t4 stageII 63, front mount IC, full 2 1/2 exhaust, no cat/ bullet muffler. all parts less than 1 year old.

It has developed a terrible ignition like( best i can describe it) miss, snap crackle, pop @ 4500 rpm+ this is while driving or just reving the car in neutral.
No codes set. Things I had done so far with no luck.

Tried new cap/rotor wires plugs. Tried gaps from 25-35 many different ranges of plugs champions rn9yc, rn12yc, ngk ur4
Distibuter shutter is tight.
Swapped coil, hep, o2 sensor
With car running I am getting 13.8v to coil / all grounds 13.8v
Swapped lm's even went back to a 2bar map and lm

Fuel pump goes to over 100psi when line is pinched
Base fp was 55 with 3bar/32 with 2bar
Fuel filter replaced
Fuel pressure rises with boost 1-1
Boost lowered to 10#

All timing is correct
Played with cam timing ( from where it wouldn't start to falling on its face at 4k)
12*
#1TDC

Cylinders compression 160-180

I just replaced the tps and sds earlier this year.
Unpluged all extras. alky inj, dawes.

Car starts and idles fine, drives fine until the high rpm.

Any ideal, therories appreciated.

Greg

[Frank]

Sounds like youa re blowing the spark out... try gapping the plugs to 20

[puppet]

Bad gas?

[BIG PSI]

I just got rid of my miss: it ended up being the wires on the body ground and the coil positive and negative wires were getting crud on them. I took a dremel to them and now the miss is all gone and runs great to 5,500 rpm

Chuck

[unluckyty]

Frank, shouldn't be blowing out spark, was running 25# at a gap of 30 before with no problem, will giv it a try though.

Puppet, ran it almost empty woking on it yesterday,has 5 gallons from another source, still problem.

Chuck, going to check, redo, and add grounds this morning.

Thanks for The ideals guys.

Greg

[unluckyty]

Ran new grounds from battery to all normal grounds, still no go

Greg

[bn880]

Swap the power module for a test.

[unluckyty]

Trying to get ahold of a PM now.

Man I hope that is the problem.

Thanks, Greg

[deuce dodge]

take out good seeming distriutor and try another one....maybe have a friend let you swap entire bundle.....all the way to plug/coil wires..........will rule out many things..........worked for me ..than i swapped one thing at a time and found bad distributor bearing wobble ..very slight ......but what a nightmare.

deuce

[unluckyty]

update, still not running right.

Things tried so far;

Power module swapped
Checked and made sure grounds were good/clean from battery out.
Distibuter seem nice and tight( I don't have another to switch though)
Plug gap down to 24 problem seems worse.
Changed batteries out, no difference.

Car starts to buck missfire from 4k+ and will not rev over 5k

Things noticed; after market shift light will flicker while acting up(but it is set for 5200rpms) I have unhooked it from the coil though and problem is still there.
Have tried (5) different cals no luck, three 3bar, and 2 2bar
3 different maps (2) 3bars and a 2bar
Adjusted fuel pressure all over the range/ tried stock reg too.

It sounds like cam timing to me. but it look's right on( have reset it numerous times) Ignition timing never moves stays right on 12*, oil pump intermediate shaft teeth look good.

I'm going to pull the cam spocket to see if it jumped the keyway.

Sorry for the book but I have researched this alot over the past few days, maybe I can cram all the information into this one thread for future needs.

Thanks once again for your help.

Greg

[bn880]

I think you have a wiring fault somewhere, specifically from HEP to LM. (my best guess)

[BIG PSI]

update, still not running right.

Things tried so far;

Power module swapped
Checked and made sure grounds were good/clean from battery out.
Distibuter seem nice and tight( I don't have another to switch though)
Plug gap down to 24 problem seems worse.
Changed batteries out, no difference.

Car starts to buck missfire from 4k+ and will not rev over 5k

Things noticed; after market shift light will flicker while acting up(but it is set for 5200rpms) I have unhooked it from the coil though and problem is still there.
Have tried (5) different cals no luck, three 3bar, and 2 2bar
3 different maps (2) 3bars and a 2bar
Adjusted fuel pressure all over the range/ tried stock reg too.

It sounds like cam timing to me. but it look's right on( have reset it numerous times) Ignition timing never moves stays right on 12*, oil pump intermediate shaft teeth look good.

I'm going to pull the cam spocket to see if it jumped the keyway.

Sorry for the book but I have researched this alot over the past few days, maybe I can cram all the information into this one thread for future needs.

Thanks once again for your help.

Greg

Hey Greg

Would you want me to come over to your house with the Turbo Acclaim and we can pull some parts and try them in yours....????

Chuck

[85glht]

Tried new cap/rotor wires plugs.

What kind of plugwires do you have??

[unluckyty]

Ok, cam timing is perfect, keyway is fine.

What kind of plugwires do you have??
Best brand the local autozone carries, have tried a couple different set that I have lying around. Never had issues with them before (12.9@105)

Chuck Thanks for the offer, I have swapped or replaced most everthing on the car, It might come to something like that eventually I let you know.


Greg

[BIG PSI]

Ok, cam timing is perfect, keyway is fine.

What kind of plugwires do you have??
Best brand the local autozone carries, have tried a couple different set that I have lying around. Never had issues with them before (12.9@105)

Chuck Thanks for the offer, I have swapped or replaced most everthing on the car, It might come to something like that eventually I let you know.


Greg

That's what friends are for, to help one another... Let me know

Chuck

[unluckyty]

New info for current problem.

Engine will backfire at 4k-4.5krpms. This is in neutral, with light throttle or full throttle stab. Same on road driving.

New things tried, ran a ground wire to each LM ground input, no change.

Could it be weak valve springs? thats where I looking next.

Greg

[unluckyty]

Springs looked fine, replaced them any ways, with springs from a spare roller cam head. The spings looked beefier than the 87's slider though.

Oh well next, I am going to try another HEP.

[BIG PSI]

Well did you ever get the miss to go away. We haven't heard anything from you in awhile.

Chuck

[Rattlesnake]

Springs looked fine, replaced them any ways, with springs from a spare roller cam head. The spings looked beefier than the 87's slider though.

Oh well next, I am going to try another HEP.

Disconnect the TPS and try it.

[unluckyty]

I let is rest for a few days Started to to go over things again, yesterday.

New Mopar HEP no luck.
If I disconnect the TPS, it will not rev, hardly at all.
Resolded some wires at the map

I was still thinking it had to be something mechanical, because the problem would happen, at around 4k+ no matter what thottle position, boost level, driving or in neutral.

I looked at the intermediate/oil pump gears through the distributer hole, and showed some uneven wear. There was some play between the two, but I didn't think it was too much.

I think while I was trying it with the tps unplugged, I had one loud back fire, then I couldn't get it restarted. It had jumped time.

Looked at the gears again now you could see they were defenitly fubbared.

Was this was my initial problem? It never changed timing at all before, just would break up at 4k+.

Car ran like a champ up untill that rpm range.

Try to get them replaced this week sometime, maybe
a miracle will happen and the problem will be fixed.