Slow/hard start after injector install. Please help.
Slow/hard start after injector install. Please help.
Hey guys,
After installing my AMS/Precision 680cc injectors and got the new flash to scale for them, I've noticed my car has been somewhat difficult to start when it is already warm at operating temperature. Typically there is no problem whatsoever in the mornings, just after the car has been driven within the past hour or so.
I changed the fuel pump to no avail. On the dyno, the flash idle looked a little lean, but everything was totally fine as the car revs up through the powerband.
I'm wondering if it could be the flash or the injectors themselves? The fueling is fine at WOT, just lean at idle and hard starts when already warm. Thoughts?
After installing my AMS/Precision 680cc injectors and got the new flash to scale for them, I've noticed my car has been somewhat difficult to start when it is already warm at operating temperature. Typically there is no problem whatsoever in the mornings, just after the car has been driven within the past hour or so.
I changed the fuel pump to no avail. On the dyno, the flash idle looked a little lean, but everything was totally fine as the car revs up through the powerband.
I'm wondering if it could be the flash or the injectors themselves? The fueling is fine at WOT, just lean at idle and hard starts when already warm. Thoughts?
Its been that way for me w/ the 680cc and the 880cc injectors since I upgraded to V3.2. With the 680cc injectors and the V3.0 I don't remember having that problem. It's damn annoying though.
Originally Posted by jj_008
Its been that way for me w/ the 680cc and the 880cc injectors since I upgraded to V3.2. With the 680cc injectors and the V3.0 I don't remember having that problem. It's damn annoying though.
Originally Posted by pjsevo8
I had the same issue with the precision 680s but from what i remember reading somewhere that is the way that they start. could be wrong tho...
PJ
PJ
Thanks for the replies so far. Anyone else?
hmmmm...i have greddy 660's and no problems. i had a tube mani and gt3076. now i'm waiting on a v550 to arrive. hope i don't have your problems with those new injectors. i'll let you know if i ever get my turbo. lol
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I hate to say this, but it seems like Shiv's injector scaling is slightly off. Either that, or the XEDE starts to playa-hate on all larger-than-stock injectors at startup or when idling.
My car startup and idle was noticeably smoother after I let Martin at AMS reflash my ECU. However, the jury is still out on how well it will work with the XEDE, since I only had the car for a couple of days and ran it on ECU only before it went back to AMS for some other things that are being worked on.
I should have some final answers in the next 3 weeks or so.
l8r)
My car startup and idle was noticeably smoother after I let Martin at AMS reflash my ECU. However, the jury is still out on how well it will work with the XEDE, since I only had the car for a couple of days and ran it on ECU only before it went back to AMS for some other things that are being worked on.
I should have some final answers in the next 3 weeks or so.
l8r)
Originally Posted by Ludikraut
I hate to say this, but it seems like Shiv's injector scaling is slightly off. Either that, or the XEDE starts to playa-hate on all larger-than-stock injectors at startup or when idling.
My car startup and idle was noticeably smoother after I let Martin at AMS reflash my ECU. However, the jury is still out on how well it will work with the XEDE, since I only had the car for a couple of days and ran it on ECU only before it went back to AMS for some other things that are being worked on.
I should have some final answers in the next 3 weeks or so.
l8r)
My car startup and idle was noticeably smoother after I let Martin at AMS reflash my ECU. However, the jury is still out on how well it will work with the XEDE, since I only had the car for a couple of days and ran it on ECU only before it went back to AMS for some other things that are being worked on.
I should have some final answers in the next 3 weeks or so.
l8r)
If that's the case, I'd think its because there are so many different injector sizes and there are 650s as well as 720s. 680 is kind of a weird size, so maybe I have a 720cc flash? I dunno.
Originally Posted by Noize
I'm wondering if it could be the flash or the injectors themselves? The fueling is fine at WOT, just lean at idle and hard starts when already warm. Thoughts?
So, we know what is happening, but as to why it's happening isn't clear. It's almost as if the injector capacity is less than advertised, but I'm not sure as to why that would be. Also, if you accidentally received the wrong impedance (e.g. high), that could cause a problem as well. Having the wrong impedance is almost certainly why AEM EMS users cry about long cranking times - the EMS is configured for lower performance, high impedance injectors (go figure) and the EVO uses low impedance injectors. It's also why they have to use unusually large injectors - because AEM is too cheap to include a low impedance driver pack, which is a ripoff.
The first thing I'd do is verify that you have the correct impedance injectors, because it sounds to me like you don't. If there are no issues there it may be due to a scaling problem that the ECU can adjust for in closed loop, but AFAIK, the cranking cycle is a static function and does not adjust itself based upon closed loop feedback.
Last edited by Ted B; Apr 6, 2006 at 06:51 AM.
Originally Posted by Ted B
If it starts fine when cold but not warm, it seems like your cranking cycle and idle are too lean. The way ECUs typically work is they sample ECT a the onset of cranking, and use this to determine the injector duty during the cranking cycle. With a cold ECT, the ECU will richen the cranking mixture, sort of like a virtual choke. With an ECT nearer operating temperature, the fuel mixture upon cranking can be reduced by 50% or more as compared to when cold.
So, we know what is happening, but as to why it's happening isn't clear. It's almost as if the injector capacity is less than advertised, but I'm not sure as to why that would be. Also, if you accidentally received the wrong impedance (e.g. high), that could cause a problem as well. Having the wrong impedance is almost certainly why AEM EMS users cry about long cranking times - the EMS is configured for lower performance, high impedance injectors (go figure) and the EVO uses low impedance injectors. It's also why they have to use unusually large injectors - because they are too cheap to get the $300 low impedance drive pack, which is a ripoff anyway.
The first thing I'd do is verify that you have the correct impedance injectors, because it sounds to me like you don't. If there are no issues there it may be due to a scaling problem that the ECU can adjust for in closed loop, but AFAIK, the cranking cycle is a static function and does not adjust itself based upon closed loop feedback.
So, we know what is happening, but as to why it's happening isn't clear. It's almost as if the injector capacity is less than advertised, but I'm not sure as to why that would be. Also, if you accidentally received the wrong impedance (e.g. high), that could cause a problem as well. Having the wrong impedance is almost certainly why AEM EMS users cry about long cranking times - the EMS is configured for lower performance, high impedance injectors (go figure) and the EVO uses low impedance injectors. It's also why they have to use unusually large injectors - because they are too cheap to get the $300 low impedance drive pack, which is a ripoff anyway.
The first thing I'd do is verify that you have the correct impedance injectors, because it sounds to me like you don't. If there are no issues there it may be due to a scaling problem that the ECU can adjust for in closed loop, but AFAIK, the cranking cycle is a static function and does not adjust itself based upon closed loop feedback.
Best post evAr. Thanks Ted!
I think it is definitely either the impedance or the flash itself, and I'll get Shiv to have a look at the flash when its on the dyno at our Dyno4mance dyno day in May.
I thought if I got like a 720cc flash with these odd sized 680cc injectors, it might behave that way. Another thing that was interesting is that I have very low percentages pulled out of my MAF table. This also leans me toward flash, but we'll just have to see.
Originally Posted by Ted B
If it starts fine when cold but not warm, it seems like your cranking cycle and idle are too lean. The way ECUs typically work is they sample ECT a the onset of cranking, and use this to determine the injector duty during the cranking cycle. With a cold ECT, the ECU will richen the cranking mixture, sort of like a virtual choke. With an ECT nearer operating temperature, the fuel mixture upon cranking can be reduced by 50% or more as compared to when cold.
So, we know what is happening, but as to why it's happening isn't clear. It's almost as if the injector capacity is less than advertised, but I'm not sure as to why that would be. Also, if you accidentally received the wrong impedance (e.g. high), that could cause a problem as well. Having the wrong impedance is almost certainly why AEM EMS users cry about long cranking times - the EMS is configured for lower performance, high impedance injectors (go figure) and the EVO uses low impedance injectors. It's also why they have to use unusually large injectors - because AEM is too cheap to include a low impedance driver pack, which is a ripoff.
The first thing I'd do is verify that you have the correct impedance injectors, because it sounds to me like you don't. If there are no issues there it may be due to a scaling problem that the ECU can adjust for in closed loop, but AFAIK, the cranking cycle is a static function and does not adjust itself based upon closed loop feedback.
So, we know what is happening, but as to why it's happening isn't clear. It's almost as if the injector capacity is less than advertised, but I'm not sure as to why that would be. Also, if you accidentally received the wrong impedance (e.g. high), that could cause a problem as well. Having the wrong impedance is almost certainly why AEM EMS users cry about long cranking times - the EMS is configured for lower performance, high impedance injectors (go figure) and the EVO uses low impedance injectors. It's also why they have to use unusually large injectors - because AEM is too cheap to include a low impedance driver pack, which is a ripoff.
The first thing I'd do is verify that you have the correct impedance injectors, because it sounds to me like you don't. If there are no issues there it may be due to a scaling problem that the ECU can adjust for in closed loop, but AFAIK, the cranking cycle is a static function and does not adjust itself based upon closed loop feedback.
Seth, do you have a pocket logger? If yes, log your fuel trims and post up what they are. Both short term and long term.
Originally Posted by Smogrunner
This post is a perfect example of why Ted B should be an Evom Guru. Great post Ted.
Seth, do you have a pocket logger? If yes, log your fuel trims and post up what they are. Both short term and long term.
Seth, do you have a pocket logger? If yes, log your fuel trims and post up what they are. Both short term and long term.
I've had it on the dyno, though, and she's LEAN at idle. I think its just because I bought this goofy injector size and should've picked up a more conventional size. Once Shiv checks the flash, I think all will be well.
Question: How do I know the impedence on these injectors vs what the correct value is?