Misbehaving engine, It was time for something to act up, right? Options

[BigDBass]

We drove the 914 to my wife's cousins' graduation party about 45 minutes away, and on the way home some recently emerging engine (mis)behavior really started showing up.

It sorta "hops" or "skips" occassionally while cruising at a steady RPM (mid-3000s).

Now a new thing: When I really open up the throttle, it seems to stumble a little bit, and I hear some popping sounds that maybe is backfiring? It's not a big BANG by any means, just pop pop pop while I can feel a lack of power.

I just filled up the tank, so maybe the gas was sub-par? I've been using the normal grade unleaded, but this was a brand I don't really know, in a different county.

(Also, I think this is a separate issue: until it warms up, it idles poorly, at very low RPMs and dies a few times. Dave-O mentioned adjusting the idle bleed screw in his PPI results.)

[bd1308]

First Issue: Check/Recalibrate or Replace your Throttle Position Sensor (TPS). For test purposes, you may unplug this and drive...if the stumble goes away you found your porblem. The car works fine without the sensor.

Second Issue: Missing or Frozen Auxillary Air Regulator (AAR). Check if this is frozen by a visual check when warm, a blow-through test when warm, or by trying to see if air gets sucked in when warm. I guess either yours is gone -OR- it needs to be unstuck.


b

[Bartlett 914]

Hi Dan.

I am still for keeping things simple first. I suggest you look at the points. Open the distibutor cap and look at the points. Use a tool and open them wide and look to see the condition. Both sides should be flat. Often a pit on one side and a point will develop on the other side. If this is seen, file smooth or replace. Use your manual and reset the distance. Sure, could be the TPS or the CHT or lots of things but I would look there first. Also look at the inside of the cap. If there is a fine line going around the inside at the top, this is a sign of a crack where carbon can develope a short circuit between spark plugs. Next I would look at the plugs.

Mark

[Dave-O]

I would agree with Mark about keeping things simple...and the points are a great place to check. From my experience, I have filed old points making them work perfectly again only to have the same problem a few hundred miles later. They are cheap and it is best to just repace them if possible.

If the simple things like points don't cure it, it sounds a lot like when my Throttle position swtich was wore out. It has a set of metal "fingers" that drag over contacts. Over time the fingers wear into the contacts causing them to not make accurate contact.

You will have to give a little more explanation to the idleing. What do you mean by "poorly". Does it idle too low causing the motor to die? Or does it sound like the engine is missing causing the poor running? Does this happen at all when it is hot? At what RPM does the motor idle hot and cold? These questions well help us figure out what is causing it.

When I drove it I felt like it was idleing at a little too low of an RPM...But I never had a chance to really get the motor warmed up.

[T wing]

Hey, I gotta agree. Check the points, check the timing. Mine was running similar and that took care of it, except for the kinda lurchy thing around 3k. I've heard the TPS on that one, but havn't gotten rid of the problem yet on my car so I'll let you know when I do.

[BigDBass]

Ok, I'll start with the points. Just so happens that that's one of the few spare parts I have. (IMG:style_emoticons/default/smile.gif)

The car supposedly had a "tune-up" before I received it, but I have had no luck after several attempts to get details of what (if anything) was done apart from an oil change (if that?)

By poor idle, I mean the RPMs are very low and it dies. Like 200RPM or so, too low to even read it. The idle stays in that low RPM range all the time at stoplights etc, but after it warms up it stays running. It sometimes bounces a little from ~100RPM to ~800RPM briefly when idling at a stop.

[Dave-O]

Ok, I'll start with the points. Just so happens that that's one of the few spare parts I have. (IMG:style_emoticons/default/smile.gif)

The car supposedly had a "tune-up" before I received it, but I have had no luck after several attempts to get details of what (if anything) was done apart from an oil change (if that?)

By poor idle, I mean the RPMs are very low and it dies. Like 200RPM or so, too low to even read it. The idle stays in that low RPM range all the time at stoplights etc, but after it warms up it stays running. It sometimes bounces a little from ~100RPM to ~800RPM briefly when idling at a stop.

I would try backing out the idle bleed screw a little bit. I'm not familiar with the 2.0l throttle set up but maybe somebody else can give you a little help locating the screw.

[BigDBass]

Last weekend I took a ride over to visit Chris(auggie91420) and in no time flat he adjusted the dwell and timing. The idle smoothed out and the backfiring and power loss seem gone. Even better, I see how to do it myself next time! Chris pointed out that my points looked new, but the cam in my dizzy is beginning to show signs of wear.

The backfiring and power loss had magically gone away for a week or so before. On the way to his place, however, it came back in a bad way, making it difficult to get up a few hills and "off the line" from stoplights, much to the chagrin of traffic behind me! (IMG:style_emoticons/default/wink.gif) The ride home was much more enjoyable.

I have had two very brief moments of backfiring since then. Also still have the occassional stumble (mostly on decel or steady cruising RPM) but it's not too bothersome yet.

The idle RPM still seems a bit low, so I may try to find and adjust the bleed screw if it keeps up.

Thanks to those that chimed in, and to Chris who came to my aid yet again!

[Dr Evil]

914 (when in disrepair), looks like a sports car, drives like a VW bus!