85 turbo - coughs on heavy accel load

Depending on the timing of this "chug" event relative to when you mash the accelerator, it could be that the computer is detecting an overboost condition and is momentarily killing power to the ASD relay to bring the situation under control, or it could be something less exotic. Your first step is to check for flash codes.

To check the computer codes:

With the engine off, switch the ignition key on-off-on-off-on, leaving it "ON". Do not go to "start", just "on" during this procedure.

Watch the "Check Engine" or "Power Loss" light. It will turn on, then go off, then will begin to flash-out any trouble codes that have been stored. For instance, if it flashes:

flash flash flash

flash flash flash flash flash flash flash flash

flash flash flash flash flash flash flash flash flash flash

Then you have a 12 (one flash followed by two) a 35 (three and five) and a

55 (five and five). 55 means "end of codes" or, if by itself, "No codes stored. Check the codes and report what you find.

Maybe you should diagnose the problem systematically and fix what's broken.

Yes, you are overdue for a fuel filter by about 20,000 miles if you're lazy, or 30,000 miles if you're smart.

What else is overdue on your car...?

DS

breaking

Ok folks I dumbly forgot to check for any problem codes first, I'll check tonight. Did not notice the light coming on when problem occurs but this is with the top down in the sun going 60 so wasn't exactly looking for it, will observe it next time it happens. Will report back what I find. thanks...Frenchy

Oops the car is right outside, duh. Ok even though I just cleaned the battery terminals since the last time I noticed the problem (the time before last that I drove it), I just checked and sure enough I have a

12 code (battery recent disconnect) and a 45 code (overboost) and 55 (end test). If I pull on the overboost rod HARD with both hands, it moves away from the diaphragm and returns back ok. Free but hard to move, normal I suppose. How far should the rod be able to be pulled? Seems like about an inch. So what pushes the rod out of the diaphragm, the exhaust pressure? And the small hose is a vacuum hose to modulate it? Or are both hoses vacuum and they move the wastegate with just the negative vacuum (boost)? Have to wait till I get home to check the condition of the hoses. thanks again...Frenchy

12 = "Start of Codes" when read via the dashboard light. 45 = what I expected you'd find.

Yep, there should be stiff spring tension on it, alright. But, you may want to remove the wastegate actuator rod from the wastegate lever and make sure the lever swings freely. If it is binding, it will cause overboost. Hitting the wastegate shaft with Mopar P/N 4318039AB penetrating fluid (do not substitute) usually eliminates the binding condition.

That's about right.

No, intake manifold pressure (under boost).

Your idea here is more or less correct, but there's no such thing as "negative vacuum". Boost is considered positive pressure and is measured in pounds per square inch (PSI). Vacuum is considered negative pressure and is measured in inches of Mercury (in. Hg). Both are considered relative to atmospheric.

If there is a leak anywhere in the hose running to the wastegate actuator, overboost will result. Same if there's a faulty or sticking wastegate actuator vacuum control solenoid.

And my question from before stands: You're long overdue for a new fuel filter, so what else has been let slide?

Heyyyy, I just put on 4 new tires this week, noticed a busted CV boot and had them fix that at same time and changed oil and filter, I always keep oil and transmission fluid topped off, I slapped on a new timing belt recently, new distrib rotor, and I keep the fake wood varnished. I did notice I had let the power steering go almost dry so after refilling it I had them flush it out and refilled it again. I was thinking of getting a new Sebring but I can't let go of this darn Woodster!...Frenchy

I've never heard of penetrating fluid before -- what's the distinction between penetrating fluid and penetrating oil?

Pure slapstick!

OK, that's good, but you've also got 50,000 miles on the fuel filter...! No insult is intended, just factfinding. How long since the entire crankcase ventillation system was serviced (much more than just replacing the PCV valve)? Spark plugs, plug wires, distributor cap? Air filter? How long since the throttle body was cleaned?

It's the new name for what Mopar used to call "Manifold Heat Control Valve Solvent".

Dunno, good question. 4318039AB (and its predecessor 4318039) smells quite unlike any penetrating oil I've ever used, and the smell is definitely not one of petroleum distillates. It also has a strange consistency. But nothing else works even close to as well on heat riser valves and suchlike.

DS

filter...!

replacing

Bingo, it was the bottom vacuum hose on the wastegate, it's rotting into friggin' cracked, melted rubber goo and had a big gash in it where it connects to the nipple. Was out of sight, and out of mind : \ Guess this explains the damn wandering idle speed I tried to diagnose but could never figure out too. Yes it's got newer plugs, wires, dist cap, air filter, and I cleaned the throttle body like a clock back when I was trying to fix the goofy idle but gave up and lived with it. It would only do it sometimes, would quit doing it for a while, then start up again, and depended on whether car was warmed up sometimes. Apparently was just that rotten hose crack heating up and letting in a bit more vacuum some times than others. Off to buy some new hose tommorrow and will try to do better job of checking all the vacuum hoses this time too (I've found and fixed a few cracked plastic tube hoses in there before). Replaced the dist rotor once when the little plastic alignment pin broke and rotor just spun freely, that was a bitch to figure out! And I'll get another fuel filter. What do I need to do to clean the PVC system other than cleaning the valve? THANKS EVERYBODY!..Frenchy

There y'go. Easy fix.

*REPLACE* the valve if it's been on there a few years. Inspect *all* the hoses and rubber elbows in the system. Don't forget the one at the left rear corner of the camshaft cover, at the other end of which is a crankcase inlet air filter that needs periodic replacement.

DO NOT USE PLATINUM PLUGS OR BOSH PLUGS< USE ONLY CHAMPION< i belive they were rn12yc, some plugs will mess with the timing of the power module and cause all kinds of idle problems. Almost like it is searching because the timing is flucuating so bad

DO NOT USE PLATINUM PLUGS OR BOSH PLUGS< USE ONLY CHAMPION< i belive they were rn12yc, some plugs will mess with the timing of the power module and cause all kinds of idle problems. Almost like it is searching because the timing is flucuating so bad

Dang, that's odd... I knew that part number sounded familiar, and sure enough that is as best I can figure the modern equivalent of the stock spark plug for a '56 Packard or Stude Golden Hawk. Never seen it used anywhere else.

Nothing really to contribute other than to comment on that, and make a mental note to ask for plugs for a '85 2.2 turbo next time I need a set for a Packard motor. Saves a lot of explaining, it does.

nate

Note in particular that the hoses in the convolute tube that run along the back of the valve cover, and the fuel injector wiring harness, have a tendency to get cooked.

Sounds to me like simple ignition weakness. Plugs and/or wires shot, distributor cap worn out (did that model still have a distributor?), coil weak. The spark has the hardest time jumping the gap under the highest compression pressures, and that happens at low-to-mid RPMs and wide-open throttle. Any weakening of the spark will result in hesitation.

Dan

IIRC, RNxxYC is the stock plug for smallblock Mopars, where xx indicates heat range (12 & 14 being typical). So there are a few million applications for you :-) Big block Mopars use the RJxxYC (shorter thread reach) series plug.