Here's the basics.'87 lingenfelter 383(factory)219 cam,timing @8 degrees,Bosch 26# injectors @47lbs,dyna mod ignition module,Bosch plat plugs @ 50thou,tps .54 volts,no arcing,no leak down on injectors,no codes.Emissions all removed,no vac leaks and everything seems perfect.
Few weeks ago at the strip experienced slight miss above 4000 at WOT.Then I fitted the superam in place of the old TPI system and boy did the RPM limit jump but still with the miss.Just put in the PCM chip hoping for a cure all.
First the car wouldn't idle so I reset it as per Gordons directions and now it's OK at around 700.Bit lumpy but that's the cam.
Gently on the gas and it pulls all the way up to about 6300-I chickened out
WOT and anything over 4000,bang pop boom.
Increased fuel pressure and it does seem to get better as far as the miss is concerned but at idle if you stand behind the car it will kill you.Called Lingenfelter and the really unhelpful guy reckoned my setup should run 58psi.I don't believe him for some reason.
One interesting fact was having tried time and time again to get the history on this car from Lingenfelter including talking to John before his untimely demise was when I pulled the chip stuck inside was a note that said Lingenfelter racing,87Y,180,700,and a signature.
Anyway I digress.Can this thing be plugged into something that will tell me if this is ignition or fuel related because I don't know which way to go next.Thanks in anticipation.Dave.

 

I would rig up a fuel pressure gauge and see if you're losing pressure when the car begins to miss.

Paul

 

Fuel filter or pump would be worth looking into. A few other places to look... 35 gap on the plugs, plug wires

 

I had a similar problem once. No codes or anything. Turned out to be the ignition module. It was an aftermarket unit, I put the stock one back in and all was fine again.

 

I would check fuel filter. Sounds like its pluged

 

with the above. Check for the basics -- fuel and spark.

 

Check your spark plug gag, .050 is too much for the ignition system on my 1986. I had the same problem at WOT and the problem only went away when I reduced my gap to .035. My ignition is in good shape but it is all stock.

 

i would agree, check your fuel pressure @ WOT, also check your TPS voltage @ WOT <5.0v
another option is put a scanner on it AZ should have one for use as a loan-a-tool, just not sure if they will have the adapter for the OBDI connector, but they might.

 

sounds like you might have broken a valve spring at the track

 

Nothing broken,at least not a spring.If I don't floor it it runs like a top all the way up to 6000.
Anyway I'm in the process of changing the plugs and the module.Plugs are starting to be fun because when i rebuilt the thing I put in the plugs before attaching the headers and dropping it into the car.and two are impossible to change.Have to be constructive tomorrow and fabricate a wrench.Keep it coming guy's.Thanks.

 

You are in open loop at WOT, could be the MAF as well. But fuel and spark are definitely questionable, ignition module wouldn't suprise me.

 

anybody remember rel3rd going through this? he played with it, and played with this n that, and it turned out to be a bad cam.
Bob finally gave up and did a compression check, all was well, then used a dial indicator on all the rockers, and he got different readings depending on the wear. (i think)
Anyway, it would rev to the moon as long as he didn't mash the throttle. same M.O.

 

Oh,Oh, has someone had a bevvy or two.
I don't know Rel3rd or bob but my comps are OK as are my rockers and my cam has been performing for over twenty years now.
How do you dial in a rocker???
(I think)
As for MO's-I hope you fly your avatar and not be one of the guys that fix it.That would be really scary.

 

Brains needed

 

plugs @50 w/out msd 6al etc. should probably be changed to 35-40, and I would hook a laptop to it w/appropraite software (tune might need some work). Tape a FP gauge to the windshield and see what it does at WOT. That 219 should idle smooth if the tune and everything else is right.

 

I'm not familiar with the lingenfelter 383 but,

If your fuel pressure is OK, check your MAF. Dirt build up on the heated wire will reduce the signal from the MAF to the ECM, and lean out your engine to the point of a misfire. If this is the case, it can be cleaned.
How about the distrubutor cap? If you haven't replaced it yet, it could be cracked. If it is an ignition misfire, the extra fuel at WOT would add extra resistance to the ignition system, and the spark could be jumping around inside a cracked cap. You will usually see evidence of carbon tracking inside the cap if this is the case. Worn distributor shaft bushings can cause random ignition misfires upstairs as well. Would you say it is an erratic misfire, or more of a steady one when it does it?

 

All the above suggestions are good. Yeah, 20 yr old cam, but are the lifters 20 yrs. old too? Just wondering since you're reving more if you"re not getting a little valve float do to a weak lifter(s). Just a thought.

 

Hey people are just trying to be helpful, don't get an attitude. The way you check cam lift with a dial indicater is mount one near the rocker arm so that the pin is pointing down onto the valve side of the rocker. Turn the engine by hand and record the amount of lift, movement of the rocker against the valve. Do all the rockers, they should be the same. If not, you have a lobe(s) going flat. This isn't common, but it does happen.

Paul

 

sounds like a dizzy prob. or a rounded cam lobe.sometimes you can see it by eye, with the valve cover off turn the motor over and look at the rockers,If one or a couple are real bad you will see a rocker not rising as much as the others.

 

Have you checked for vacume leaks?Some have had a problem with getting the superram to seal up?what about a worn timing chain?Just some guesses,could be a lot of things.Do a compression test,put a vac. gauge on it?Check valve springs,cam lobes,dizzy