'91 Talon will not rev....yes, I searched.

[georgiaboy]

'91 Talon AWD/turbo/automatic. All stock except 255 lph in-tank and a shift box for the automatic.

When it turns over, it takes a while to start. If the throttle is manipulated, it dies, unless it is fluttered and even then it may rev or may not rev.

I changed the MAF to another one. If the MAF is left unplugged, the ECU will throw it in limp mode (?) and it will rev, but still has a flat spot off of idle; but does rev much more freely. If I plug the MAF back in, it still stalls. I have a 2g MAF adapter and when using a 2g MAF the problem is still there.

I checked the ECU. One of the bigger caps was leaking, so I re-soldered another in, but the problem still persisted.

I checked ref voltage at the TPS; .6V at closed throttle, 4.9V at WOT.

Car had been sitting a while, but we added good gas after changing the pump.

I hear the ISC (like IAC, but I guess this car has an ISC) clicking quickly and unrhythmically when the key is turned on.

It has new spark plug wires and BPR6ES plugs in it.

Any ideas?

I thought about CTS, but wouldn't the problem still be present even with the MAF unplugged (when I CAN get it to rev)?

-Les

 

[nightracer91]

Usually the coolant temp sensor will cause an extended crank, sometimes a no start at all but will start right up with a shot of starting fluid. If it starts right up with starting fluid, i'd check the temp sensor real quick just to see if you can rule it out.

 

[siege]

This might be a long shot but i would check my ground wires to the maf i had this problem with my maft and it ended up being a broken ground wire in the harness. good luck i hope you get her fixed.

 

[georgiaboy]

Thanks, guys. I will isolate those grounds tomorrow. I should probably terminate at the battery, huh?

I wasn't smelling a strong fuel smell during cranking, so I didn't think it was rich. But, I will check that CTS in the morning as well. Doesn't the absence of CTS feedback to the ECU make the ECU think it is very cold, thus making the mixture rich? Anyway, good idea....thanks for the tip. I will check it tomorrow.

I just wanted to make it clear that I tried a different 1g MAF as well as a known good 2g MAF, but the results were the same. It seemed neither selection was telling the ECU to supply the correct amount of fuel.

This only happened recently. I have cranked the car and driven it without issue, have cranked the car and only had noid or fire on two cylinders (assuming CAS problem there, but it hasn't come back), and am now having this problem after changing the plugs and wires.

What does allowing it to run and rev without the MAF plugged in specifically eliminate?

-Les

 

[georgiaboy]

I found the problem: the fuel line going from the top of the fuel pump in the tank to the hard line that goes through the fuel pump/sender assembly mounting flange was split. Sometimes I would get fuel pressure; other times I would not. I checked fuel pressure a couple of times and had it, but finally checked it again and found that the fuel pressure would jump up and then fall quickly.

I did check the CTS and resoldered new connectors to it as they looked *iffy*.

Thanks for all of the help!

-Les