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914World.com _ 914World Garage _ 76 2.0l FI stock engine bucks under 2000 rpm and load

Posted by: jdlmodelt May 8 2013, 07:09 AM

Hi guys,
My 76 2.0l stock Fuel Injected engine is bucking when I press on the throttle to accelerate when the engine is under 2000RPM. Above that the engine is smooth and strong but below that point when I step on the throttle going down the hiway, it either bucks, stutters and doesn't accerate or doesn't buck but doesn't accellerate either. It is backfiring a little more than ussual as well. It let out a couple of big bangs at the tail pipe yesterday when I was down shifting to a stop light at lower speeds. So, running super rich at lower RPM? I changed the timing last week to smooth out the low idle. I'm guessing that may be some of it?

BUT, I was wondering if the throttle possition sensor needs to be adjusted along with the timing? It seems like there is some kind of relationship in the lower RPMS amongst the ignition timing, the injector timing, the throttle position sensor and the anti-backfiring valve?

Posted by: 914itis May 8 2013, 07:31 AM

I would start with the tps, check points, dwell and vaccum advance at distributor.
I had an issue of the ame except that mine was at 3300. I rebuilt my dizzy and problem went away.

Posted by: falconfp2001 May 8 2013, 09:13 PM

This is a common occurrence with the TPS being the culprit. After time a groove will develope on the TPS board. Only solution once it has the groove is to replace the board or find a nice used TPS.

Posted by: jdlmodelt May 24 2013, 08:36 PM

QUOTE(914itis @ May 8 2013, 07:31 AM)

I would start with the tps, check points, dwell and vaccum advance at distributor.
I had an issue of the ame except that mine was at 3300. I rebuilt my dizzy and problem went away.

Adjusted TPS, then cleaned points, then it wouldn't start at all. I had filed the points, sprayed them with brake cleaner, then used the air gun to blow the distributor body out real good. All with the distributor still installed in the engine. Well, I finally pulled the distributor out of the engine and pulled the injector points out of the distributor and found lots of crud that I had just blown down further when I cleaned the points. So, I cleaned everything really good. put a tiny film of lube on the shaft and put it all back in. This is the smoothest this engine has run!