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tyhoppy

15+ Year Contributor
119
0
Mar 27, 2006
New Bethlehem, Pennsylvania
Have a problem. Put a motor in my talon tsi and it is cutting out between 4 and 5 thousand rpm if I give it alot of gas. If i ease into it I can rev all the way up. but once i push the pedal down more it'll cut out and kind of bounce. While it is cutting out I can hear a clicking sound coming from the area of the ecu. I have already checked for boost leaks, and tried new plugs and wires, and also tried a different coil pack and a power transistor. Please help.... ASAP. Thanks. -Tyler
 
sound like fuel cut to me. turn the boost down and see if it goes away.

but if it's not that - I had a similar problem when I wasn't getting enough voltage from my alternator. the ecu would just shut down completely and make a hard bang. it was like fuel cut, but not.

go over everything.
 
well I am running completely stock... I did happen to have my battery die on me today and when I jumped it it only ran for a little while untill it shut down.. It does act like fuel cut. but possibly the alternator. However, my alternator is only a year old... ? Would the clicking sound be coming from the computer if it were fuel cut? or if it were the alternator problem?
 
Just because your alt. is relativly new doesn't mean that it isn't dying. They can come broken brand new. I would check the alt. output voltage while idling using a DMM (Digital Multi-Meter). There is a large guage wire (should be red) going from the alt. to the battery. Put the red (positive) DMM lead on the connector under the red rubber cover on the alt., then put the black (negative) DMM lead, and ground it out. Make sure the DMM is set to 10Amp's, and AC Analog. Or you can bring it to a shop, and have them hook a VAT 45 up, and test it that way. On the VAT if the reading goes below 9.6v its probably junk.
 
Sounds like your running off the battery.

Charge it over night and if the car runs file you'll know you have a problem with the charging circuit. That may be as simple as you blew the alternator fuse or you lost the alternator. Our cars are hard to alternators duw to their location rignt next to the exhaust and under the power steering pump. Heat and oil can quickly kill them but the cheap parts most rebuilders use to meet the autoparts store prices doesn't help.

It's too bad that DSMs didn't come with voltage gauges. The warning light doesn't always come on when your not charging and the first warning is the car looses power when you give it any throttle just before the ECU shuts off from low voltage

Steve.
 
ok.I have a battery/alternator tester that I'm gonna use today to check it. But I dont' think that's it, cause I fully charged the battery while at work last night and after work took it for a drive and it still does it... If it is fuel cut would it make the clicking sound like the ecu shutting down. If that is what the clicking sound in the ecu is?
 
steve said:
It's too bad that DSMs didn't come with voltage gauges. The warning light doesn't always come on when your not charging and the first warning is the car looses power when you give it any throttle just before the ECU shuts off from low voltage

Steve.
Click to expand...


And this is exactly the reasoning for installing an autometer voltage guage on my new project TSi AWD.

But Steve I wouldn't recommend charging it over night. Trust me Ive seen what happen's when you over charge a battery LOL, it start's pouring white smoke. This was due to the battery being over charged by this kid in my class...but the next step isn't as funny as seeing that kid's face...it then turn's to a dirty bomb, and can explode. So if I were you I'd charge it till it battery is at 12.68v (without anything charging it when testing it). There will be a few .xx volts more due to it being charged just then. Then start it up, and drive it, this will probably only be good for 20minutes before the problem comes back if it is your atlernator causing you to run off battery voltage.

Dustin
 
tyhoppy said:
If it is fuel cut would it make the clicking sound like the ecu shutting down. If that is what the clicking sound in the ecu is?
Click to expand...
No fuel cut doesn't cause the MPI relay to click. That's caused by the voltage dropping or the ECU rebooting. Since you think that the voltage is good during your test the next guess would be capacitor leakage damage to the ECU. Pull it and check.
 
Ok. I'm sure it is something in the charging/voltage system, because on my logger i get readings that range from 10 to 13 volts with the ignition on and the car not running. I should be getting a constant voltage from the battery like that though, right? Also, when it does cut out the reading on the logger goes down around 9-10volts and the battery light comes on then goes out right away. Is the fluctuation of voltage normal with the engine not running and the key on, at the logger? With my tester i get a constant 12.6 volts at the battery and when running i get a constant 14 - 14.5 at the battery. So I am thinking this could possibly be the computer not reading the voltage right? could this be it? Any clues? Thanks.
 
I had the ecu apart a week ago and checked everything out and it looks brand new inside. I believe it was rebuilt back in 2005, because it has that date written on it with some initials and had warranty void if removed tape on it.
 
Do an AC Analog check across the battery. There should be less then .5v's present at the battery. Voltage readings are looking good, but when the cutting out occur's is when it goes below the specified minimum allowance. I would check the alyernator belt. Look for glazing on the underside. It could be slipping when you get on it putting it under heavy load, and making the alt. max itself out.
 
all other signals are constant and appear to be correct. how do I do an AC analog check? and what exactly is it? Also you say voltage reading are looking good. should my voltage, at the logger, be jumping around when the key is on and engine not running? with the logger it reades between 10 and 13 varying. but with my batter/alternator tester I get a constant voltage at the battery.
 
tyhoppy said:
all other signals are constant and appear to be correct.
should my voltage, at the logger, be jumping around when the key is on and engine not running?
Click to expand...

I expect those are real voltage readings from the ECUs perspective and not the side effect of the ADC circuit being bad then. No it shouldn't be jumping around, it should be pretty stable until you start cranking when it will drop and bounce back once you stop

Can you try measuring the voltage somewhere else in the car like the lighter socket?
If you see it there too you might have a bad battery connection.
 
thanks. I'll do that. and if i do get a steady reading somewhere else, that means it is more than likely the ecu, correct?
 
where would I be able to find which wires are for the power lines for the ecu from the mpi relay?
 
I know about vfaq. I don't know what i was thinking not looking there. So what am I actually checking on this wire? voltage? should I check continuity at this wire and at another point in the harness somewhere?
 
I just saw that 56, 63 and 66 are both for the mpi relay. I am guessing I just ground off of anywhere on the chasis and check the voltage of both wires separately? And if the correlate with the reading I have been getting with my logger then there is a problem with that wire before it gets to the ecu?
 
Try looking at 102 or 107 for the voltage referenced to chassis ground or 101 and 106.

Since I can't edit the VFAQ I'll have to point out that pin 56 is the control line for the fuel pump relay and pins 63/66 the control line and sense for the MPI relay. So those pins are pluued to ground by the ECU to turn on the relays. They are not voltage sources.

Pin 103 is the backup power source from the radio fuse to maintain the fuel trims and other long term settings.
 
tyhoppy said:
I just saw that 56, 63 and 66 are both for the mpi relay. I am guessing I just ground off of anywhere on the chasis and check the voltage of both wires separately? And if the correlate with the reading I have been getting with my logger then there is a problem with that wire before it gets to the ecu?
Click to expand...

Check for voltage. Continuity is pretty useless because all it needs is one tiny wire to show continuity. Also with key on/engine off it may vary a few tenth's of a volt due to system's checking themselves, but not varying +/- 3 volt's.

I agree with Steve after looking at the pin out, check 101, and 106 for ground. Also check 102, and 107 for power, but you will want to check both for how current passes through. High amperage to get through the wire, and there's likely to be high resistance.
 
Hey Steve,
If there is a problem with this circuit to the ECU can relay be added to the circuit and just use the radio line as a switch for a good 12volt line? I'm having similar problems and the radio circuit is the one that seems to be dropping off. I've seen the tps jump with the motor not running and my ISC will work off and on by my logs.
 
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