Stock Injectors and H/C
Thread Starter
TECH Enthusiast
Joined: Nov 2008
Posts: 525
Likes: 3
From: Saint Joseph, MO
Stock Injectors and H/C Hey guys, I recently installed heads and cam on my car and when I went to get my car tuned and the tuner said I would not need to upgrade my injectors. (I brought FAST 36lb with me for him to install, and he said I wouldn't need them). My concern is now the car is running really bad, I have a flashing check engine light that comes intermittently, the car surges very bad between 1500-2000rpm. And after 2krpm when you give it any gas it is very jerky. I have checked the plugs and wires and the grounds and they are all good. I was thinking that maybe my problem is that my stock injectors are maxed out at 100% and they are burnt up. Does anyone have input on this? I put down 428rwhp and I think thats probably to much for the stock injectors and they are the source of my problem. We already bought a new fuel pump thinking that was the problem but after looking into the injectors, we think this may be the problem. If anyone has any light to shine on this please help!
Yes if you were cam only you would be ok, but with the addition of heads and the extra incoming air, you will need bigger injectors. 36# are perfect. Find a new tuner as well, sounds incompetent.
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Did it drive ok after the tune or is this a new issue?
Injectors don't burn up if they are too small. And if too small, I doubt you would have got to the RWHP you did.
Your tuner could have told you what the duty cycle was at full power. He should still have that data.
I'm sorry, but I'm not understanding your logic?
Ron
Injectors don't burn up if they are too small. And if too small, I doubt you would have got to the RWHP you did.
Your tuner could have told you what the duty cycle was at full power. He should still have that data.
I'm sorry, but I'm not understanding your logic?
Ron
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Did your tuner tell you the duty cycle was 100%? When an injector goes static it can burn up, but if you had an injector go bad you should be able to pinpoint the injector when you checked the plugs. You may want to check your valve springs.
Thread Starter
TECH Enthusiast
Joined: Nov 2008
Posts: 525
Likes: 3
From: Saint Joseph, MO
It ran fine after the tune, no I didn't ask him what the duty cycle was at. My father has auto enginuity software and when we hooked it up to my car, at idle it was showing a few missfires on every cylinder. So I am not sure what to think. So lets just say my injectors are reaching 100% duty cycle at WOT, what could happen to my injectors? The reason I want to prove that it is the injectors so I can show my tuner that this was his fault for telling me not to install the 36lb fast ones I brought the day I had my car tuned.
For whatever it's worth, my car is also heads and cam... stock 243 heads with EPS cam and my IDC is 90-95% on WOT. My car runs great. Solid AFR 12.8-12.9 across the board.
Does it make it right? It is a precautionary and recommended to upgrade the injectors while the IDC is at 90-95%. I have SVO red tops on standby when I upgrade my intake to FAST 92/TB 92mm.
Find out your IDC first/AFR on WOT, troubleshoot/isolate the problem instead of jumping into a conclusion.
scan it and see what is going on. I might be wrong, but I doubt it is injectors. Things you might trouble shoot are MAF, map sensor, TPS etc. Start by trying to pull codes and go through a process of elimination . MAf is easy just unplug it and see if it runs better in open loop. When I had a broken spring it would idle fine and under part throttle there was a miss (nothing bad) and it actually pulled decently at WOT. As it got worse I started receiving all shorts of SES codes that had nothing to do with the actual problem.
Thread Starter
TECH Enthusiast
Joined: Nov 2008
Posts: 525
Likes: 3
From: Saint Joseph, MO
scan it and see what is going on. I might be wrong, but I doubt it is injectors. Things you might trouble shoot are MAF, map sensor, TPS etc. Start by trying to pull codes and go through a process of elimination . MAf is easy just unplug it and see if it runs better in open loop. When I had a broken spring it would idle fine and under part throttle there was a miss (nothing bad) and it actually pulled decently at WOT. As it got worse I started receiving all shorts of SES codes that had nothing to do with the actual problem.
