RX7145

iTrader: (1)

My 84' -SE with a S4 n/a in it died on the freeway Saturday. At first I thought it was a fuel pump but I have good fuel presure. I had steve Kan tune this car two years ago and have not had a problem sence. The car will start and run for a couple of seconds then die, If I play with the gas pedal is can keep it running but just barely. I'm getting pulses at the injectors, and the injectors ohm out ok. Timing is ok and I'm getting spark at the plugs. The temp sensors all seem to be the correct temp. and the TPS works fine. What am I missing? Ideas welcome!

Thanks,
-Paul

TrboRty

iTrader: (1)

3 things needed to make a engine go, air,fuel,spark,obviously. If you have 2 of the 3 for sure i.e spark,and air, then it has to be it is not getting fuel. Just because you have fuel pressure does not mean you have volume, I have seen this happen on several cars with hard/no start concerns and "car stumbles under acceleration" problems. Also have seen a bad map sensor cause a stumbling problem also....

pluto

Logged it while you're driving your car and see when it actually does it so that you can narrow down the problem. Sounds like that it could be your staging injectors not working properly.

13b4me

Man I read that thread and just had some serious dejavu...
Right down to your avatar and the music I got playing... WHOA!!!
Sorry for butting in like that... Just wanted to record the experience... lol

pluto

I know that its not the map sensor since I provided him with two maps. One using map sensor (which doesn't work that well but it works) and the other using TPS (which is what we tuned for and in the car).

RX7145

iTrader: (1)

Well I can bearly keep the car idling let alone drive it. I think that this is a "hard faut" somehow. How could the staging change when driving with out a computer even connected? If the staging changed would't it still idle?

Thanks Pluto for helping with this.

RX7145

iTrader: (1)

I know, I'm stumped. I hooked a fuel pump up to make sure that was not happing but the same problem. And It's not a stumbling problem it's a almost a no start.

pluto

That's strange, have you done a compression test? Are all sensors working properly? If TPS doesn't move, that'll cause the car not to idle and run properly. Make sure that the TPS range from 0-100% on the data screen.

another thing you might want to do is to drain your gas. I have seen gasoline somehow go mixed with diseal and causes the car to run weird. (not saying this is your case but it could happen). You know how those guys are, they just stick the pipe in the hole and fill it up

RX7145

iTrader: (1)

The temp sensors all give the correct reading on the engine data page. TPS goes from 0-100% like it should. The car ran fine on the first 1/4 tank,also when I tested the fuel system I used gas from another tank.

I have not done a compression test but I get three "puffs" on both rotors.

RX7145

iTrader: (1)

Well I'm sure I'm missing somthing here. Is there any way to "test" the ECU?

TrboRty

iTrader: (1)

well one way would be to disconnect one of the injector connectors to a noid light and see if it flashes. that checks to make sure the ecu is pulsing the injectors, that would be the way I would check it, am I right here steve?

Max7

We did that, and all 4 checked out ok. Even ohm'd them to make sure they were within spec..... the saga goes on....

pluto

I don't know if it is the injectors or not since I staged the injectors on cells 28+ so if he's having problem crusing, its not staged injectors. If it was me, I would put a fuel pressure gauge on to see what is going on with the fuel delivery. there're only three things that makes an enigne run. fuel, compression, and ignition. If all checks out, there shouldn't be a problem. Whatever it is can't be that hard to figure out, just that I'm not there to diagnose the problem. is it possible that you somehow modified the haltech map w/o knowing it?

2Lucky2tha7

iTrader: (3)

I know this is ridiculuously obvious, but when is the last time you've changed the fuel filter?? If the filter is bad, you'll get pressure, but not enough volume. It's happened to me before---> Just out of nowhere, the engine will die and it's a bitch to start.

RX7145

iTrader: (1)

I don't see how I kould have changed the map, as I did't even have a laptop pluged in. But I reloaded the map anyway; no different.

I have a inline gauge that shows good pressure under crank/running conditions.

It seems to run ok above 2K but if you try and rev it up quickly it back fires and dies. It will not idle though. I'm starting to wonder if somthing is messed up with the primary injectors.

RX7145

iTrader: (1)

Yes I bypassed the filter useing another pump but no luck.

TrboRty

iTrader: (1)

steve, I went and looked at pauls car today. The car is def. having a fuel issue. If you pinch the return line of the fuel rail, which in turn ups the fuel pressure, the car runs fine,and does not cut out. So my question is, could a faulty map sensor cause this? I know efi systems use the map to calculate elevation. If that was reading a higher elevation to the haltech, does that not in turn cause the haltech to run a leaner mixture and could possibly be the source of pauls problem? We also tried a different fpr and that seemed to help it some. Also if you tuned his car by using just the tps, how does the haltech know how much air is entering the engine? And what purpose then does the map sensor on pauls car serve? Does the haltech use it as a elevation calculation tool like other efi systems? And could that be the source of the problem u think?

TrboRty

iTrader: (1)

any response or input pluto?

pluto

It sounds to me that his fuel pump isn't hold pressure based on your explanation The reason why N/A tunes with TPS is that there're no other easy way with the haltech to interpolate properly with the map sensor. I actually provided him with two maps, one using the map sensor while the other is using the TPS. When everything is tuned right (including the compensation map), his car should be fine in just about anywhere he drives. I think first thing is to check with the fuel pressure and see why it was doing it.

TrboRty

iTrader: (1)

paul any luck on this?