Brett

I have had this problem for a while and it has been getting wose. I thought it was the GURU setup I had so I bought a Vitesse MAF.

The good news is the car will start now but as soon as I get ANY ammount of boost the car stummbles realy badly and then wants to die. If I drive without making any boost the car is driveable. Even at WOT I can only manage 2-3psi because the stumble and cutout is so bad.

I have checked the TPS, Vacuumm, power to MAF. I still have the KLR from GURU and I am wondering if that is the culprit...

thanks for any help.

Rogue_Ant

When was the last time you pulled the plugs?

Brett

A few weeks ago when the car stoped on me and I had to tow it home. They looked a little worn. But I keep thinking its something with the KLR becasue I can go from idle to 6K with no problem as long as I don't have any boost.

Brett

If it were bad plugs or wires or rotor. Wouldn't I have the stumbling and missing regardless of boost or no boost.

Rogue_Ant

No. A weak ignition will show up much more under heavy load then lighter loads.
Lighter loads, there is less cylinder pressure, making it much easier for the spark-plug to ionize the gap. Once in boost/heavy-load, there is much more cylinder pressure, making it much more difficult for the ignition system.
I doubt the KLR is the issue.
How old are plugs and the rest of your ignition system? You said you pulled the plugs, did you re-gap them once you put them back in?

-Rogue

Brett

I believe the wires and coil are stock, not sure about the plugs, I did not re gap the plugs. So if the ignition sys is weak it would show at as little as just under 1 psi of boost?

Rogue_Ant

Perhaps - it depends on how weak the ignition system is.
How old are the cap & rotor?

-Joshua

Brett

I think they are original.

Rogue_Ant

Lol - well if they are original, then I highly suggest replacing cap, rotor, wires, and plugs.
Those are all wearing items, and after 20+ years, I'm sure are overdue.

JustinL

Sounds like an ignition problem as Rogue suggests. Try regapping the plugs as a temporary fix.

Paulyy

this sounds familiar...
as rogue said, change cap & rotor, plugs and leads.
do you have an A/F gauge?

fast951

Since you already tested TPS and "pressure" tested the intake system, with no problem found. I would look into the ignition system. If you are still using the original components (cap, rotor, wires), it's probably time to replace them regardless. Go ahead and put a new set of plugs as well (make sure to gap them).

While checking things, make sure the BOV is fine.

I have seen KLR chips causing issues, but nothing as you describe. I would address other issues before looking into the KLR box (or KLR chip).

spammajamma

just had this problem, my wires looked good and ran fine until I got on her then it was always spotty on when under boost, swapped the wires with new ones and she runs great with none of that bog under boost...my old wires were original equipment too....twenty+ years is way too old, you probably have breaks and gaps on every wire

Good Luck

Brett

Thanks guys I will change some of thoes items out and re update. Spamajama was the bog pretty severe for you.

Thinking back, I did start to have bog under load and I thought that it was AFR, Then it just got worse and worse. now it only runs ok with no load.

Brett

One other thing to note is since the problem has gotten bad it takes a few trys to start the car. Before it would fire up on the first try.