POOR RUNNING 82 FI SPIDER

[ARNO]

Can someone please help i am losing my mind with this car,it will start up and idle fine if its hot or cold and sometimes will rev really nice for a minute or 2 and then thats it ,it just wont rev it coughs and splutters you can hold the throttle on and it tries to go then dies back to idle??????????????????? here is a list of things that i have done to the car to try and find the problem ,the car as only done 39000 miles
1.replaced all vac pipes
2.replaced fuel filter and cleaned pump
3.replaced injector seals and run cleaner through tank
4.replaced spark plugs and leads
5.i have had the coil and the module checked and all ok
6.checked timing
7.cleaned all grounds that i can find
8.checked pump relay seems fine
9.checked cold start valve
10.checked aux air valve
I found that the vacuum advance was,nt working causing a vac leak so i capped the pipe ,i then started the car and ran great for about 5 minutes and then same again wont rev,this is strange but i also noticed when you put the lights ,heater blower and wipers on it rev alot better not perfect but better......as anyone else had this problem or can someone help me its driving me crackers..

[jimincalif]

Checked the coolant temp sensor? Do you have Brad Artigue's manual:

http://www.artigue.com/fiat

Also, if having all the electrics on improves things have you checked the alternator output voltage when running?

[So Cal Mark]

have you checked the flap in the afm to ensure it doesn't stick at all? Have you checked the fuel pressure? Is the intake boot in good shape without any splits?

[macawlover70]

Have you checked pressure in your fuel line with a pressure tester and have you checked the pressure regulator?

[ARNO]

Hi thanks for the replies,the intake boot is in good shape ,i have not checked the coolant temp sensor by that you meen the one on the coolant t piece,and also i have not checked pressure with a tester but it sounds ok when running,but if pressure was down why would it run better when all electrics are on????..
The alternator looks fairly new,i have checked the AFM flap with ignition on and you can hear start the pump,i have also crimped the return pipe from the pressure regulator at idle and the engine drops in rpm if you take the crimp off it returns to idle..
whats the best way of testing the coolant temp sensor???? and are they any more major grounds on the car other than in the trunk and on the inlet manifold...

Once again thanks for the replies it helps to get different verdicts on the problem

[rlux4]

The temp sensor is checked with an ohmeter. The reading should be: @14°,7-12,000 OHMs; @68°, 2-3,000 OHMs; @ 176°. 250-400 OHMs.
Do you have Brad Artigue's maintenance manual? It has a section that covers our Bosch L-Jetronic system, including some trouble shooting guides;
http://www.artigue.com/fiat/books/Artig ... 124_MM.pdf
Ron

[ARNO]

ok so i tested the temp sensor at the E.C.U plug and with the multimeter set to 2000ohms it measured 620@140f and 223@190f i also set the meter to 2000k and it measured 0.01 at both temps....i plugged the ecu back in and started it up and it was still poor but then i put the lights on and it ran like a dream for for about 10 minutes and than ran poor again??????????so i started to check all the ground to the lights which i cleaned and replaced ,i even removed and cleaned the ground from the body to the bell housing but this made no difference when i turned the lights of it was even worse...
what could it be i know that i am close to solving the problem but just cant put my finger on it,is there any more major grounds anywhere and where does the ECU ground to.

Thanks again in advance

Arno

[So Cal Mark]

ecu grounds are at the back of the exhaust cam and on the plenum. What you're describing doesn't sound like a ground problem though. Adding extra load to the electrical system via the headlights should cause more problems if you have a bad ground. If indeed the headlights are affecting a circuit in the engine management, you need to figure out which circuit changes with the lights on

[jimincalif]

Did you check the battery voltage with the engine running? After starting the car the alternator/regulator should bring the battery back up to full charge and then hold a steady voltage. You said the car runs OK for a couple of minutes the badly, then it runs OK if the lights are on. Is it possible the voltage regulator is defective and not cutting back on the charging current, allowing the voltage to get too high, and the ECU is malfunctioning at too high voltage? It would take a couple of minutes after starting for this to occur, and running all the electrical devices would pull the voltage down. Both of these fit with your description of what is happening. Also as I recall the lights and the switched power lead to the regulator go thru the same terminal on the ignition switch and connector block, so turning on the lights would pull down the current going to the alternator field, cutting back the regulator.

Put your meter on the battery, note the voltage. Start the car and watch the voltage, what does it read when the engine runs well? What does it read when the engine begins to misbehave? What does it read when you turn everything on and the engine runs well again.

This is just a WAG, I have no idea if this would affect the ECU. But like Mark said, if it were a grounding problem adding to the load would make things worse, not better.

[ARNO]

Hi there again

So i tested the voltage at the battery at idle and it was 14.13 volts if you then try rev the engine it drops to 10.86v then fluctuates to 13.92 ,,,if you then put the lights on the voltage is 13.90 volts the it revs better but still drops to 10.86v then back to 13.92v...then if you put heaters and main beam it revs perfect and the voltage is the same between 13.7 to 13.9 volts The voltage regulator looks very new its a bosch item (0192 052 006 )545 This problem as got to be electrical maybe 1 wire rubbed through to another? There is a bunch of wires where the radio used to be with plugs on the end are all these for the radio its like a vipers nest

Many thanks Arno

[So Cal Mark]

sounds more like an alternator issue than anything else

[jimincalif]

That 10.86 volt reading is bizarre, could be a fault in the alternator. I'd try running it with the power to the voltage regulator disconnected so the engine is just running on battery power. If it runs OK then the alternator is pulling down the voltage.

[ARNO]

Hi there again,so i removed the alternator last night and had is tested this morning and its fine so is the regulator,but i did notice when i took the alternator off that the adjustment bracket that bolts to the engine was very loose and i believe this is the ground for the alternator ,could this be the problem???? i shall report later

Thanks Arno

[ARNO]

Hi
This made no difference at all and even with the lights on it does,nt rev now??.what is the best way of setting up the AFM because when it idles the reostat is almost at the bottom but when you move it up by hand it rev good , the flap does,nt seem to be sticking any ideas??

[So Cal Mark]

do you have an air leak between the afm and throttle body? Restricted exhaust?