orig944

So the temp sensor is resistance is incorrect. It is telling the ECU that it is very very very hot outside, so the ECU leans the mixture out as it thinks the air is less dense. Shorting it tells the ECU that it is even hotter. From your pictures, it looks like the sensor is plugged onto the external connector with a disconnect. If so, unplug one side and try running it. It should make the mixture very rich.

papasmurf

I am not sure what you are saying about the sensor plug and unplugging one side? It is the factory AFM plug in the photo just with the rubber boot pulled back to expose where the wires enter the plug. I agree that it seems the car is running lean and of course the IAT resistance numbers seem to corroborate this. The exhaust smell on this car is strong and not particularly pleasing....a car running rich especially during warm up I can tolerate and do not find particularly offensive but this car just stinks. I ordered a used AFM last night from plyhammer to see if it will operate correctly again.

Jfrahm

Are you supposed to check the resistance of that sensor in-circuit or with the AFM disconnected?

papasmurf

Going back through the clarks garage instructions, I think you are right, that it is supposed to be measured on the AFM alone...at least that is what it implies. I just had my Dad measure the AFM for me as the car is stored at his place currently and it measured 1.16 which supposing he took the measurement correctly it is still reading lower than what the measurments stated on clarks site of "15 - 30 °C = 1.45 - 3.3 k-ohms" It is probably in the low 80's here today which I guess would correspond to the higher end of the recommended range.

orig944

Inside the AFM module. Where the sensor wires connect to the AFM connector.

Also, it will run rich always, not just during startup. This is just a test to make sure this is the problem.

Also also, do you have another multimeter laying around to measure with? Just to verify that your meter is working correctly. It is odd that both your units failed in this way.
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papasmurf

I have checked the AFM and DME temp sensor with another multimeter and have gotten almost the exact same results. I measured the IAT again this evening and it measured about 1.2 (temp was in the mid 70's so I would think it should have measured closer to the 3.3 end of the spectrum) so it is not reading correctly. The AFM I purchased has not arrived yet but I started the car and removed on the leads on the IAT senor inside the AFM. While the car was warming it seemed to run better than before but would still have some hesitation particularly right off idle. After about 5 minutes the car was fully warmed up and I would say was almost perfect with perhaps just the slightest hiccup right off idle. Revving the car and letting the revs falls before adding throttle would before cause stumbling and a backfire and it is all but gone. I want to try the same thing from a total cold start as the car usually takes about 3 times of cranking....sputter sputter...dying before it takes off and runs without issue. I want to see if the IAT reading rich will cause it to operate normally from a complete cold start like it used to. Hopefully the other AFM will arrive soon and not have any issues and I can put this thing back on the road finally. I still may purchase another DME temp sensor if I cannot get the correct readings with the one in it just to rule that out as well.

Jfrahm

When it's cranking and won't start, stop and see if the plugs are wet and if it's all of them or one more than the others.
It really sounds like you are leaking fuel into the intake and not dealing with a sensor issue. Some of your assumptions or observations are probably wrong. We've all been there.

papasmurf

I was able to work on the car again this evening for a short amount of time. I pulled the wire on the IAT to force the car to run rich again because I wanted to see how it responded when starting from cold. It started the first try where it usually would sputter for 2-3 seconds at best before for one or two tries before running. The car idled for about 5 minutes and like before, ran much much smoother with the only really noticeable stumbling coming right off idle if you aggressively applied throttle. I plugged the IAT back in and as expected it was easier to get the car to stumble and eventually backfire if you pushed it hard enough. The AFM I ordered showed up today and I measured the IAT resistance as soon as I unboxed it and it measured almost exactly the same as the previous AFM. I actually measured all three back to back and I think the original AFM's were around 1.22 and the new one was 1.25 so either the clark values are suggestive at best (FR wilk site I linked to shows similar values) or this one is defective too (I can't imagine 3 being defective though). I did pull all the plugs after shutting the car off and they all looked about the same and were all dry. If anyone has access to measuring their AFM I would be curious as to what resistance values they are getting and if they are correlating with the clarks/fr wilks numbers pretty closely.

https://web.archive.org/web/20120415...44.com/afm.htm

papasmurf

Well things are fixed...and then they are not. I finally got what I would call accurate readings from the AFM's, DME temp sensor, etc. and pulled the injector rail again to have a look at the injectors. In the process of doing so my virtually new fuel supply line got strained I guess where it screws into the rail and started leaking fuel every so slightly. Needless to say I was about to throw in the towel on the car at this point but got the fuel line sorted out and the injector pulled. I put 9V to them to test them individually and they all were firing but there was one that seemed to freeze. All the injector screens looked pretty clean and I ran some carb cleaner through the others to see how they were spraying. Not the most scientific test but I didn't want to bother sending them off for service if they were iffy in the first place. Since the one injector was looking iffy I purchased four off of ebay that were remanufactured with the bosch part number on them (at least the thumbnail showed that). The injectors arrived and none had the bosch PN which I wasn't really happy with but decided to try them anyways. The car started the first time but didn't run exactly smoothly as you would expect and died after about 30 seconds. Subsequent attempts at starting it would die almost instantly. After doing some checking I think the injectors were drawing too much current and shutting the drivers down on the DME. To test my theory I put the three original injectors that were functioning back in and one of the new injectors and the car started quickly and ran like it has not run in over a year....no stumbling, no hesitation, great throttle response, etc. So knowing that I could not run all four injectors I returned them to the seller without issue and bought the FJ11 injector that some have reported using because I thought that was what my original injectors were (they are not bosch). When it arrived it was not a pintle type like the others even though some of the photos showed it was but I tried it anyways and the car ran good but still had a bit of stumble/hesitation. Frustrated beyond all belief at this point, I bought a bosch injector that has been rebuilt and installed it today...sadly there is still stumble/hesitation so I am probably going to just order 3 more bosch injectors cause the ones I have I cannot match because I think they have been discontinued when I looked up the part number. The only difference between the time it ran great and today is I had forgot to put the injector screens back in my original injectors and did so today but I do not think they are the cause of the issue.