HELP!!!! Engine is Surging at low RPM Cruise!!!

[Cudajason]

After driving in heavy rain to Moparfest this morning, my car is not running very well.

It started to surge at idle and low speed cruise. 

I was out last week 100 plus miles and the car ran great...now, not so much....going down the highway, at 50 MPH around 2500 RPM it has a chug, I cant decide if it is missing or surging, but it is not smooth that's for sure.

I checked the plugs, that all look nice and brown.  SO maybe its not engine related.

Over 2700 RPM 70 MPH it seems to run ok...but off the highway around town it chugs pretty bad.

Any ideas on what I should be looking at?  Could it be a transmission issue???



Jason

[Cudakiller70]

Vacuum leak, maybe PCV valve

[RUNCHARGER]

Heavy rain: Look for an ignition issue or water in the fuel I think.

[Cudakiller70]

Did this start after a fuel up? Bad gas

[BigSig 6 Barrel]

..

Distributor cap ????


.

[Cudajason]

Vacuum leak, maybe PCV valve

Oh I did not think of PCV valve!  The vacuum gauge reads steady, tried some WD 40 around the carb base, no change in RPM.

Jason

[Cudajason]

..

Distributor cap ????


.

Thats what i was thinking. Looked dry!

Did this start after a fuel up? Bad gas

Yes...its a station I use all the time...but i guess it could be.

[73440]

What condition are the plug wires in ?
Any crossed wires to adjacent firing order plugs ?

[GoodysGotaCuda]

Surging but running decent is typically a lean condition or too far advanced timing. I'd say the timing magically becoming too advanced isn't too probable, but a lean condition certainly could be.

As I've mentioned here before, a entry-level wideband oxygen sensor is a REALLY nice thing to have on anything you need to tweak on. It's taken a lot of guesswork out of tuning my Warlock.

https://www.ebay.com/itm/Innovate-LC2-Wideband-DB-52mm-Kit-w-O2-Sensor-BLUE-Gauge-LC-2-3795/302709029004?hash=item467add388c:g:J4gAAOSwxH1UIP0m:sc:ShippingMethodStandard!76227!US!-1

[1 Wild R/T]

Vacuum leak, maybe PCV valve

Oh I did not think of PCV valve!  The vacuum gauge reads steady, tried some WD 40 around the carb base, no change in RPM.

Jason

Which means it's not a misfire, I agree with Mike  (Goody)  It's probably lean & a wideband O2 sensor would make positive diagnosis easy...

[BIGSHCLUNK]

 Simple things first - pull dist cap wipe it down - look for moisture or tracks created from moisture - engine heat may have dried it up. Take off fuel line - pump out a gallon into a plastic bucket - let it settle out (i been down this road a few times over the years) if the bottom of the bucket looks off color - its water. If so live w it till you burn thru it or drain the tank. My x had water once so bad (winter) i took off the fuel line it was actually ice. After that i would ck for a vacuum leak. Power brake hose maybe... not always an issue at the carb base.

[Chryco Psycho]

Rain I suspect ign  WD 40 in the dist cap helps , could be bad gas , could be bad power valve coincidentily failing

[Cudajason]

OK guys...I took the car to Moparfest  and back again today...made it which is good, but its still doing the same thing.

I took the dist cap of...its dry as a bone, no evidence of cross firing.

The engine idles well, and runs strong when you give it throttle all through the RPM range.

But cruising under 2500 RPM...or when you let off going down the highway, it just sort of jumps / jerks down the road.  When you get back on the gas it feels like it jumps into gear.

Bigs, Murray, Ian, John and I discussed it at the show today, and we think it might be the transmission going south.  The more I drive it the more convinced I am that that is the case.

Going down the road it almost feels like its jumps into gear / kicks you in the ass, as opposed to cutting out.  You can almost feel the front of the car lift.

You put it in neutral going down the road and it glides down the road smoothly, pop it back in gear and you can feel it engage.

So,  I think I am going to learn how to rebuild a transmission this winter.

Jason

[dodj]

You put it in neutral going down the road and it glides down the road smoothly, pop it back in gear and you can feel it engage.

So,  I think I am going to learn how to rebuild a transmission this winter.

Jason

And was the tach is nice and steady @2500rpm while gliding in neutral as well?

[Bullitt-]

I'm wondering if the kickdown lever is in a bind or something like that............