Help, possible AFM issues

[mikebloomfield]

I just put my fuel injectors back on. I had taken them off because after getting them cleaned, one was leaking and I wanted to get clamps on both ends. So they are back on, and not leaking.

However, the car is running very very rough. I had to turn the idle screw up very high to keep it from stalling. Idle is very rough. Above idle, car runs great. Pulls very well. Its definitely not running on 7 cylinders.

I think its my Air Flow Meter because when I start the car without plugging the AFM in, it runs the same. Car idles marginally better after idling for a while. In other words, warm or cold, at start the idle is very low but after a minute it gets better, although very rough.

Just to eliminate other stuff: Temp sensors are two years old. I had a spare injector relay, so I swapped that in. Fuel pump relay is 6 months old or so. Check the grounds at the valve cover (cleaned it just in case) and the ground wire underneath. Seems fine. And like I said, car pulls really well at speed. Just complaining at idle.

So what's my next step? How do I test? I have seen that refurb involves taking it apart and moving where the pointer tracks. If I can confirm that its the AFM, I'm just as happy getting a rebuilt one. The cover on the allen screw that allows you to set mixture is missing. So the PO was messing with it at some point.

Its an 1982 L-Jet.

Thanks for you help.

[jstobo]

From WSM.

[lfausty]

don't overlook a second third fuel inj relay.

noid light to each inj to be sure inj harness ends are good. or all connects are clipped back together good. or if you did rework the brittle/aged connectors, crimped/soldered method , new ones on to wiring harness that there good.

tronics supposedly doesn't remap but after every connections was unclipped reclipped ... before everything was in place buttoned up and battery got reconnected. maybe while something unplugged could not have reread at brains .
or if bat was never disconnected while unplugging things slight surge happened and tripped/shut down fuel inj system and disconnect reconnect will straighten it out.

[mikebloomfield]

hey guys--Thanks for the input!

I "tested" the AFM by finding a cheap used one. Unless that one was bad, its not the AFM. When I first got the car, I replaced the spark plugs. In putting the car back together, I forgot to plug in the AFM. When I started it up, it did exactly what its doing now. Which is why I suspected the AFM.

I suppose the new injector relay could be bad. I didn't swap it out until I started having problems, so its not known that the original was bad.

I think I have a big vacuum leak, either at the AFM or at the caps where the decel valve used to be. I have an o-ring and new caps on order. As well as the mounting towers for the air box, mine are all deformed. One data point I could be just making up: When I put the used AFM in, the car seemed to run pretty good and I was pretty excited. I took it out, attached the airbox and reinstalled, and then it started running like crap again. It is much easier to get the AFM snug without the airbox attached. I don't know, could be wishful thinking.

The noid light is a good idea. It makes sense to investigate what I messed with. I will make sure the injectors are firing. I had initially ruled this out for one reason: T he car is drivable. It runs pretty good over 25 MPH (once it gets over 1000 RPM or so). Until then, its just idling rough. Car is also louder, and seems to be running rich.

Does anyone think I should unplug the O2 and see what happens? If its a massive vacuum leak, I would think it would run lean, until the O2 sensor compensates for all the gas in the exhaust. Unplugging the O2 might give me another data point.

[newold928]

Try checking a Auxiliary air valve or the Cold start injector something is binding up and run some seafoam in it if you have multiple vac leaks that will cause it too i can give you a list of what it could be. But lets keep it simple at first the cheaper the fix the better. check out the sticky from mpdano it helped me alot.

[mikebloomfield]

So, after a month trying to hunt down my problem with the very rough idle, to my shame I must admit that I gave up. I took it to PowerTech in Rockaway NJ. They are very knowledgeable about Porsches, and I highly recommend them. I knew I had dropped it off at the right place when I saw three 944s lined up out front.

Anyway, it turned out to be a large vacuum leak at the injectors. It took Powertech a while to figure it out, but what happened was that the second vendor I took the injectors to did not put long enough stub hoses on one of the injectors. So, the injector didn't leak gasoline, but it didn't seat properly either.

The only good news is that in trying to solve the issue, I found a couple small vacuum leaks (like the o ring at the AFM) and now the car runs like a rhino crossed with a cheetah.

My question is regarding the second vendor. Given that he cost me money in introducing a problem that wasn't there before, what are my options? I obviously will never go there again, but do I have any leverage to demand a refund? I have the invoice from Powertech that states the problem. I guess I just need some arguments to have ready when I call him.

Thanks guys.