temp sensor or ECU?

[macawlover70]

I have very little time on the computer so I can't search the forum so I will hope someone can help me here. My fiat, an 81 fuel injected, that I have put so much work into and have learned so much about is having an issue that has me perplexed. I have replaced the ecu, put an inline fuse in for the fuel pump relay, put a new top end and gaskets for the whole top end in, put new starter, main seal, clutch, temp sensor, coil, magnetic pickup, control module, radiator fan, head temp sensors, water temp sensor on radiator, throttle position sensor, cold start valve, fuel pump, wires, cap, rotor, and plugs. WHEW! Anyway, it was running fine but the cam housing gasket was leaking a little so I took it off and replaced the gasket and when I did I changed the coil and readjusted the magnetic pick up. When I went to start it, it would idle fine but when I gave it gas it would stall. When I try to feather the gas it will try to run but will backfire a little and die. I checked the coil put the old one back on, and magnetic pickup and they are fine. It is getting spark to all four plugs and with a NOID light the injectors are pulsing. I was at my wits end so I started pulling sensor connectors while it was idling and when I took off the temp sensor on the radiator T it ran better so I tried the throttle and the engine revved pretty good but surges a little at higher RPM's. Before, when I took off that connector, it would run very bad and die. So I thought " bad sensor" I took out the sensor and checked the resistance and get about 1185 and when I put a lighter to it for heat it steadily drops like it is supposed to so I put it back in and same issue. I now think that maybe my ECU is bad but I just replaced it and don't want to do it again unless it is absolutely for sure the problem. So, my question is, is there anything else I am not seeing or checking that I should? Anyone ever had this Problem? Does anyone have a spare ECU I could borrow to use to check for bad ECU?? I would pay for shipping and insurance and can ship it back the day after I get it. If it is the ECU where is the best cheapest place to get an ECU for my car? The last one I got on this site but I think I want to get a refurbished or new one if possible so I know it’s good.

In closing, I have been working on this car for over a year and have only had it drivable for a short time. I am so close to being done with the engine part that I just want to move on to the front end work that I have planned next. So any help is much appreciated. Sorry for the lengthy post but I wanted to be sure to get it all in there cause I can only check this once a day for a short time. I can also be reached by phone and E-mail for any questions anyone needs to help me. 361-563-0220 and Macawlover70@yahoo.com
Thanks in advance for any help.
Sincere regards. Robert Daniels.

[adrians]

Have you checked for air leaks and have you got the PDF manual


http://artigue.com/?page_id=3

[majicwrench]

The odds of the ECU being bad are real slim, and it sounds like you just changed it anyway?? You need to check out that article mentioned and not guess.
SO I take it it was running fine before you replaced the cam housing gasket??? LIke was said, look for air leaks tween AFM and throttle body.

[macawlover70]

Thanks guys, I have all of Brad's stuff printed out last year. I think I love that man but can't figure out my prob. No air leaks. As I said all new gaskets with sealent on top end, new throttle body to AFM boot with hose clamps. New hose to the vacume advance. It really has me stumped. I am just going to wait I guess till I can find an ECU to borrow or can afford to buy one to check that because I can't see what else it could be. It was running fine before I changed the cam gasket and now won't run without the temp sensor being unhooked. The only other thing I can think of besides the ecu is the AFM which is the only thing left I haven't replaced. I can't afford that right now though. I believe it is definantly a electrical issue. HELP!

[2ndwind]

Two thoughts. 1) You may have a crack in the underside of your air intake tube. Particularly where the auxiliary air valve comes in. It may have gotten worse with handling or heat may open it up. $33 for a new one.

2) coincidentally your AFM failed. The AFM also has a temp sensor in it (not replaceable). I wonder if it is sending conflicting signals to the ECM? If you can stick another AFM on from somebody's running car (5 min switch), you will know if it is AFM related.

[macawlover70]

Two thoughts. 1) You may have a crack in the underside of your air intake tube. Particularly where the auxiliary air valve comes in. It may have gotten worse with handling or heat may open it up. $33 for a new one.

Checked the boot and it is good.

2) coincidentally your AFM failed. The AFM also has a temp sensor in it (not replaceable). I wonder if it is sending conflicting signals to the ECM? If you can stick another AFM on from somebody's running car (5 min switch), you will know if it is AFM related.

This is the likely culprit since it's the only thing I havn't replaced besides the alternator and oil sending unit which it abviously not those I will try replacing the AFM and if it is not that Then I will test the ECU by switching out a loaner. Wish me luck. Oh, by the way, anyone have a reasonably priced working AFM?

[So Cal Mark]

if the car starts and runs, I doubt you have a bad ECU. Normally an injector driver would fail, causing a no-pulse on the injector. Does the noid light speed up when you try to rev the engine? Since you had the cam housing off, have you verified the cam timing?

[macawlover70]

It's Alive!
I replaced the AFM and it started right up and runs great. Steve is the winner. Thanks for all the help. Man I have learned so much from you guys. When I first got here I didn't even know what a noid light was, where the ecu was, anything at all about fuel injection, or that a car even had an AFM. But thanks to your advice and guidance I have become very knowledgeable about my Fiat.
Other than a small oil leak out the back/side of my cam housing on the dist' side the engine is all done and It's on to the Front end. I will someday return the help you all have given me when I have more access to the Internet but until then I just want to Thank you all again. Especially Ron who has been there for me every step of the way.