So, the weather got a bit warmer and I finished a couple of things that needed finishing. This means I had a bit of time to spend on the 245 that just wouldn't die. This is the car I picked up for $500 a while ago that got hit by some drunk and that I tried to sell. Nobody bought it, although a couple of people from here looked. (Hi, Klaus!) Since it apparently liked being where it was I started fixing it a bit at a time. Some hammering and plugging a couple of leaks were done in the fall.

Over the course of last week I pulled the intake and replaced the gasket, readjusted the throttle switch, replaced the TB gaskets and the TPS O-ring (that was one petrified piece of rubber) and replaced the injector seals.

This had the effect of making it start real nice and apparently taking care of some or all of the vacuum leaks. Braking does not kill a cold engine any more. Idle is better.

The bad part is that there is still something in the engine compartment making tons of noise (alternator?) and that there was some backfiring on acceleration. Hitting the gas makes it pop a couple of times before it actually accelerates. Noise I don't care about at this point, but the backfiring and the lag between pedal and motion is troubling me.

So, where should I look next?

As xmopar suggests, it may be a lean fuel-air mix. The mix doesn't fire when it is supposed to but a bit later.

Check Lucid's posts about blocking a hose to pass emissions. (High NOx produced in lean conditions.)
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1980 245 Canadian B21A with SU carb but electronic ignition and M46 trans in Brampton, Ont.

Hows the AMM? A bad one caused some backfiring and lag in my 89....

The adjustment screw on the AMM is exposed. I think the previous owner monkeyed with it in the attempt to fix the idle.

I wonder if there is any info on calibrating the AMM...

I wonder if there is any info on calibrating the AMM..

Yes, but you have to have a CO meter to adjust it properly. Go to www.k-jet.org and navigate to the Green Books for the 240. Down the page about half way are two books for the early LH system. The procedure is in one or the other, I don't recall which.

There are also procedures for testing the AMM and a troubleshooting guide.


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Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)

Looks like I can get a used AMM for about $40. Since I don't have a CO meter that might be a worthwhile route.

My only experience is with the later ones (LH 2.4), which aren't adjustable, so I don't have any advice for you there. Do you have a known good one you can swap in to test? If it were me, I'd try to pick up a used one, just to have a spare. IIRC, yours should use the 007, which is pretty readily available.

Howdy,

You know, I get more satisfaction out of every mile in my $500 245 (now sporting a new control pressure regulator) than just about any car I have ever owned. Over 40K miles to date. I love it.

Braking does not kill a cold engine any more.

But, does it cause the engine to stumble? If so, replace the check valve at the booster.

backfiring on acceleration. Hitting the gas makes it pop a couple of times before it actually accelerates. Noise I don't care about at this point, but the backfiring and the lag between pedal and motion is troubling me.

Very lean. How is fuel delivery? New filter?

I think you are still getting a ton of unmetered air. It may be that idle was so bad before that the improvement only allows you enough revs to really pull air.

Make sure the idle air bypass is not open all the time. Check the vacuum lines down to the EVAP canister. Look for splits in the larger and longer vacuum hoses.

If no air leaks, check the ECT to make sure it tracking engine warm up. If it reports a hot engine all the time, the ECU will lean out the mixture.

Don't forget that weak spark can produce symptoms that would make you swear the car is running lean.


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Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)

Braking does not kill a cold engine any more.

But, does it cause the engine to stumble? If so, replace the check valve at the booster.

Valve is new. I originally thought I had a leaking booster, but then I ran the engine with the booster disconnected and the port capped off and saw no difference. Booster holds vacuum - even some time after engine shutoff pulling the check valve will get you a loud hiss.


Very lean. How is fuel delivery? New filter?

I haven't tested the pressure. Filter is probably not recent, I had that in the plans but didn't do it yet. Have the replacement filter, though.

I think you are still getting a ton of unmetered air. It may be that idle was so bad before that the improvement only allows you enough revs to really pull air. Idle was pretty bad. I am making gradual improvements trying to rule things out.

Evap hoses were OK last time I checked, but that was last year.

Now, IA valve and ECT are real possibilities. Haven't looked there yet.

Hello Jpaganel,


A intake manifold gasket leak is a quite common fault. You should test the gasket by spraying starting fluid or propane around the joint between the manifold and the cylinder head. If you spray and the idle changes, then you know that the gasket has failed.

Please post back and let us know how you are doing Jpaganel!


Goatman

Already got the new gasket on. That's what made the idle better.

The old gasket was pretty far gone - it was hardened and crumbled when touched.

If the igntion system is up to par (cap, rotor, wires, plugs, good coil), backfiring usually means a lean condition of the air/fuel ratio.