F4i woes

[Marc Jaxa-Rozen]

Well, we've spent the better part of the last two days trying to get a sign of life out of our F4i/PE setup, and we're utterly stumped at this point. The same engine ran fine last fall in our '04 car, and a similar parallel setup is working well on the dyno.

Basically the engine seems to get spark and fuel, but we're hard-pressed just to get it to burp around a bit while cranking. We've swapped around two sets of injectors (together with fuel rails and FPRs), both of which definitely work fine, and plenty of spark plugs. Crank trigger wheel positioning also definitely is correct, and so is the crank signal polarity (we've tried both ways, anyway). No problem with battery voltage, and we've tried various starting compensations in reasonable ranges and beyond. We just get occasional backfires from fuel pooled in the exhaust, so nothing that appears to point to a particular problem. The coils/injector banks fire correctly from the PE Diagnostics menu.

Seems to me like a really gross timing error, but as I mentioned the trigger wheel is fine and we haven't touched the valvetrain. So...we're pretty much out of ideas, and that front page countdown is starting to scare the hell out of me. Any suggestions really would be welcome.

Thanks!

Marc Jaxa-Rozen
École Polytechnique de Montréal

[Marc Jaxa-Rozen]

Well, we've spent the better part of the last two days trying to get a sign of life out of our F4i/PE setup, and we're utterly stumped at this point. The same engine ran fine last fall in our '04 car, and a similar parallel setup is working well on the dyno.

Basically the engine seems to get spark and fuel, but we're hard-pressed just to get it to burp around a bit while cranking. We've swapped around two sets of injectors (together with fuel rails and FPRs), both of which definitely work fine, and plenty of spark plugs. Crank trigger wheel positioning also definitely is correct, and so is the crank signal polarity (we've tried both ways, anyway). No problem with battery voltage, and we've tried various starting compensations in reasonable ranges and beyond. We just get occasional backfires from fuel pooled in the exhaust, so nothing that appears to point to a particular problem. The coils/injector banks fire correctly from the PE Diagnostics menu.

Seems to me like a really gross timing error, but as I mentioned the trigger wheel is fine and we haven't touched the valvetrain. So...we're pretty much out of ideas, and that front page countdown is starting to scare the hell out of me. Any suggestions really would be welcome.

Thanks!

Marc Jaxa-Rozen
École Polytechnique de Montréal

[Colin]

I've never used PE but the first time we got an engine going with motec we had similar problems (you've probably already checked it all but just in case here's a few ideas)
1. Firing order (i know it's basic but we f**ked it up! i thought the setting in the ECU changed the order but with motec you have to hard wire in the fireing order)
2. get a timing light and make sure the ignition is firing consistently (if a trigger sensor is behaving erratically you may still get spark and fuel injection but the timing will be all over the place)
3. if your running sequential ignition/injection make sure your not 360 crank deg out

are you getting a good strong spark? And what trigger sensors are you using?

[B Lewis @ PE Engine Management]

Marc,

Are you running the same mufflers on the dyno and last years car? We had a team several years ago that we helped out with similar symptoms. It turned out they had repacked the muffler to pass noise and in the process restricted flow so bad the engine would not start. Other things to check:

Bad Gas - Do you have fresh gas? It will never start on turpentine

Coil Wiring - Are the coils wired properly?

Manifold Leaks - Large intake manifold leaks can create similar symptoms

Fuel Pressure - Are you monitoring fuel pressure and do you have adequate fuel supply?

Injector Wiring - Are the injectors wired with 12 volts? We have seen other customers wire them to 5v and they will still "click" with the diagnostics but will not flow much fuel.

Plug Condition - Are plugs clean when you try to start (you can clean them effectively with a propane torch) and are they wet when you pull them out after trying to start? If you are dumping a bunch of fuel to start the plugs should get wet.

Crank Errors - Are you seeing any crank errors when trying to start?

Just a few things to try. Also we will be in Pontiac on Wed afternoon if you need help.

[Bob T]

I also have never worked with a PE ECU, but like Colin have had similar problems recently getting an engine going with a Motec. A couple of other things that haven't been mentioned yet that you might try....

1.) Cam sensor - from what I've read it seems that you have crank pretty well covered. Although you probably already have, check to make sure that your cam sensor is wired correctly and the signal is good.

2.) It could be a problem with the ECU itself, although these problems are rare, they do happen. We discovered that our Motec engine sensor ground pin was faulty, we didn't get any errors, but when we grounded it to the chassis and the engine fired right up, when it was grounded to the pin - nothing.

This was, this was of course after the entire harness had been gone over 5 times, removed and taken to the dyno to try and run the engine down there.

[Marc Jaxa-Rozen]

It fired right up into a steady idle after we swapped out the plugs again for another set. I really hate IC engines sometimes.

Marc Jaxa-Rozen
École Polytechnique de Montréal

[scooter2131]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">fired right up into a steady idle after we swapped out the plugs again for another set. I really hate IC engines sometimes.

Marc Jaxa </div></BLOCKQUOTE>

Is it just idling right now or is it ok throughout the rev range? We were having the same issue where our dyno motor ran fine but the one in our car ran like piss. Moving the timing wheel was a major culprit. Also, check for pressure leaks. In our case it was faulty wiring of the injectors that was causing us to only run on 2 cylinders. Check all that stuff if you're still having problems. Good luck and we'll see you at competition.

[Chris Boyden]

The propane torch trick on the plugs seems to help with starting problems on a consistent basis. they can be touchy little bastards.

[Didier Beaudoin]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by scooter2131:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">fired right up into a steady idle after we swapped out the plugs again for another set. I really hate IC engines sometimes.

Marc Jaxa </div></BLOCKQUOTE>

Is it just idling right now or is it ok throughout the rev range? We were having the same issue where our dyno motor ran fine but the one in our car ran like piss. Moving the timing wheel was a major culprit. Also, check for pressure leaks. In our case it was faulty wiring of the injectors that was causing us to only run on 2 cylinders. Check all that stuff if you're still having problems. Good luck and we'll see you at competition. </div></BLOCKQUOTE>

We've just had a great testing session, everything's fine, the car rocks. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Matt Gignac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
We've just had a great testing session, everything's fine, the car rocks. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif </div></BLOCKQUOTE>

Where are you guys testing this year? SRA again?

We're having some troubles as our usual testing location has been rented out for the next week.

Matt Gignac
McGill Racing Team

[B Lewis @ PE Engine Management]

Didier, Marc.... Glad to hear you are up and running again.

[Agent4573]

Hey, if anyone with a PE-ECU1 wants a nifty trick to getting a perfect idle here it is. Flip the wires on the pickup wheel. Don't know why or how it works, but if you connect your pickup wheel backwards the car will idle at 1000 rpm perfectly. But thats all it will do no matter how much fuel or air is added, it just sits there and idles..... Of course one you connect it the right way it runs fine.