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Car is a 92 L98. Mostly stock minus a few bolt ons.
I had some reman Bosh III fuel injectors in there for quite some time. The car was never easy to start, but once it would start - it ran fine. Definitley started quicker with the factory injectors.
Fast forward to today, I came across some new 24lb "HFB" Bosch EV1 Injectors. I noticed these had slots in them where you could use the factory style clips to keep the injectors in place on the fuel railing. I went ahead and put the clips in, everything looked good.
Car started instantly, like it used to. But - it feels like its got a slight miss at idle. The RPM will move around abit between 600-700. Its not a HUGE miss, the car wont stall - but its noticable, and the car has a slight shake. Once you get on the throttle its fine. I also notice it smokes abit at idle, which it didnt before.
Are these 24lb injectors too much for this setup? I have an adjustable FPR, which is at about 43psi with vac line attatched. Should I lower the psi a bit?
Another thing i noticed - the base of a few injectors seems to get just barely wet. This could be my imagination. Should I have NOT used the injector clips with these style injectors?
Car is a 92 L98. Mostly stock minus a few bolt ons.
I had some reman Bosh III fuel injectors in there for quite some time. The car was never easy to start, but once it would start - it ran fine. Definitley started quicker with the factory injectors.
Fast forward to today, I came across some new 24lb "HFB" Bosch EV1 Injectors. I noticed these had slots in them where you could use the factory style clips to keep the injectors in place on the fuel railing. I went ahead and put the clips in, everything looked good.
Car started instantly, like it used to. But - it feels like its got a slight miss at idle. The RPM will move around abit between 600-700. Its not a HUGE miss, the car wont stall - but its noticable, and the car has a slight shake. Once you get on the throttle its fine. I also notice it smokes abit at idle, which it didnt before.
Are these 24lb injectors too much for this setup? I have an adjustable FPR, which is at about 43psi with vac line attatched. Should I lower the psi a bit?
Another thing i noticed - the base of a few injectors seems to get just barely wet. This could be my imagination. Should I have NOT used the injector clips with these style injectors?
Thanks for your help.
First, you really shouldn't adjust the fuel pressure to compensate for over sized injectors, you need to adjust the fueling parameters in the tune. Why 24 lbs. injectors instead of something closer to the stock 21 lbs. spec.? If you plan on mods or already have them in place, you are going to have to tune the fueling anyway, so........
Secondly, the threads I have seen lately address the leaky Bosch III issue as an installation issue. It is reported that you need to push the injectors into the manifold first, being sure they are seated. Use a lubricant on the O-rings to ease the process as the Bosch IIIs are slightly larger on the manifold end. Once the injectors are carefully installed into the manifold, seat the fuel rail down onto the injectors being careful to seat the O-rings into the rail. Bolt down the fuel rail to hold everything together. The purpose of the clip was to aid in assembly of the "factory" parts, not actually hold the injectors in place after assembly so the clips are not necessary. By using the clips, you may not have enough engagement into the manifold and is the reason it is recommended to install them into the manifold first. HTH!
See this thread https://www.thirdgen.org/forums/show...wpost&t=724142
Last edited by bigal55; 09-14-2015 at 12:38 PM.
Reason: added link to pertinant thread
I happened to come across the injectors, and I figured they were close enough to the stock 22lb injectors to try. Plus they are new, and I've had bad luck with remans.
Anyways - at this point I suppose I should try to reseat them. I'm assuming a slight air leak could cause this funny idle I'm having. If that doesn't resolve it - any suggestions for a prom burning service? I just don't have the patience to pickup on the whole DIY-PROM thing at this point.
Originally Posted by bigal55
First, you really shouldn't adjust the fuel pressure to compensate for over sized injectors, you need to adjust the fueling parameters in the tune. Why 24 lbs. injectors instead of something closer to the stock 21 lbs. spec.? If you plan on mods or already have them in place, you are going to have to tune the fueling anyway, so........
Secondly, the threads I have seen lately address the leaky Bosch III issue as an installation issue. It is reported that you need to push the injectors into the manifold first, being sure they are seated. Use a lubricant on the O-rings to ease the process as the Bosch IIIs are slightly larger on the manifold end. Once the injectors are carefully installed into the manifold, seat the fuel rail down onto the injectors being careful to seat the O-rings into the rail. Bolt down the fuel rail to hold everything together. The purpose of the clip was to aid in assembly of the "factory" parts, not actually hold the injectors in place after assembly so the clips are not necessary. By using the clips, you may not have enough engagement into the manifold and is the reason it is recommended to install them into the manifold first. HTH!
See this thread https://www.thirdgen.org/forums/show...wpost&t=724142
Just saw the link. Looks like most the of leaky issues there are at the rail end. Mine was more so on the manifold end, and it wasn't pooling or anything like that. Just the bottom of one or two injectors looks "moist". I should also mention the injectors I have look different than southbay's. See link below:
Originally Posted by bigal55
First, you really shouldn't adjust the fuel pressure to compensate for over sized injectors, you need to adjust the fueling parameters in the tune. Why 24 lbs. injectors instead of something closer to the stock 21 lbs. spec.? If you plan on mods or already have them in place, you are going to have to tune the fueling anyway, so........
Secondly, the threads I have seen lately address the leaky Bosch III issue as an installation issue. It is reported that you need to push the injectors into the manifold first, being sure they are seated. Use a lubricant on the O-rings to ease the process as the Bosch IIIs are slightly larger on the manifold end. Once the injectors are carefully installed into the manifold, seat the fuel rail down onto the injectors being careful to seat the O-rings into the rail. Bolt down the fuel rail to hold everything together. The purpose of the clip was to aid in assembly of the "factory" parts, not actually hold the injectors in place after assembly so the clips are not necessary. By using the clips, you may not have enough engagement into the manifold and is the reason it is recommended to install them into the manifold first. HTH!
See this thread https://www.thirdgen.org/forums/show...wpost&t=724142
Well I went ahead and did a few more tests. Ill keep updating in here until i resolve this.
I sprayed some carb cleaner around the base of each injector. I believe the injectors are seated properly as there was no reaction to this.
I checked the rail PSI again, and surprisngly the rail is NOT holding pressure. This must be an intermittent issue, as just a few days ago it was. Nothing was changed between now and then. The PSI drops within seconds. Pulled the rail assembly and verified injectors are not leaking. either FPR or check valve at this point. I do hear a slight hissing after engine shut off. Not sure if this is related.
I'm also not sure if this would cause the idle issue. Does anyone here have expierence with 24lb injectors on 350TPI with pretty much just headers? If all the car needs at this point is a custom tune, so be it. But I'd like to make sure thats likely the issue before I throw money at problem thats not there
I've made a quick video of the idle issue, just to put it in perspective. Engine is ice cold here, you can barely tell there is anything wrong until you notice the car is shaking a bit. As you get closer to the exhaust you can hear its off - also notice there's a bit of smoke there - from what I can assume is an extremely rich mixture.
Went over everything again. Noticed that the fuel rail PSI would drop after being primed, but very slowly. Said F it and put the factory injectors back in. PSI doesn't move. Car runs perfect.
Originally Posted by 92-Formula
Well I went ahead and did a few more tests. Ill keep updating in here until i resolve this.
I sprayed some carb cleaner around the base of each injector. I believe the injectors are seated properly as there was no reaction to this.
I checked the rail PSI again, and surprisngly the rail is NOT holding pressure. This must be an intermittent issue, as just a few days ago it was. Nothing was changed between now and then. The PSI drops within seconds. Pulled the rail assembly and verified injectors are not leaking. either FPR or check valve at this point. I do hear a slight hissing after engine shut off. Not sure if this is related.
I'm also not sure if this would cause the idle issue. Does anyone here have expierence with 24lb injectors on 350TPI with pretty much just headers? If all the car needs at this point is a custom tune, so be it. But I'd like to make sure thats likely the issue before I throw money at problem thats not there
I've made a quick video of the idle issue, just to put it in perspective. Engine is ice cold here, you can barely tell there is anything wrong until you notice the car is shaking a bit. As you get closer to the exhaust you can hear its off - also notice there's a bit of smoke there - from what I can assume is an extremely rich mixture.
If the injectors are leaking from the rail end then they are either too short or one of the orings is bent.
There was no sign of leaking externally. Originally I mentioned the bottom of the injectors were "moist", but that was just oil I used to lube the orings prior to install. Im just glad the car runs fine with the factory injectors. I've now got 16 injectors laying around. Going to contact the select of the last 8 (black bosch iii's) since I do believe they were not functioning correctly.
Hey there,
Going through the same issue on my 87. I built an L98 with 9.5:1 forged speed pros, smooth idle comp roller cam, summit aluminum heads, roller rockers, edelbrock hi flow ported intake, slp runners, and the bosch 3 injectors. After driving 15 mins and coming to a stp it has a vibration/miss at idle. it should idle smooth as glass. Valves are adjusted, plugs, wires, distributor is new. I did the service mode power balance check, found when i unplugged #7 injector the rpm raises 50 rpm??? all others drop. These injectors are noisey to begin with but i think they are leaking. i ohmed them all at 16-17 ohms. Noid light checked the harness, all good. I will not pull the intake apart again to test for internal leaks, if that happens you best believe i will have 8 different injectors in my hand. I bought the injectors from ebay, the yellow ones. I probably should have went to southbay, they give a sh** about quality control. I don't think these other guys on ebay do. Southbay, would you want these pieces of junk? After i buy a set from you im going to just throw them away anyway...
Hey there,
Going through the same issue on my 87. I built an L98 with 9.5:1 forged speed pros, smooth idle comp roller cam, summit aluminum heads, roller rockers, edelbrock hi flow ported intake, slp runners, and the bosch 3 injectors. After driving 15 mins and coming to a stp it has a vibration/miss at idle. it should idle smooth as glass. Valves are adjusted, plugs, wires, distributor is new. I did the service mode power balance check, found when i unplugged #7 injector the rpm raises 50 rpm??? all others drop. These injectors are noisey to begin with but i think they are leaking. i ohmed them all at 16-17 ohms. Noid light checked the harness, all good. I will not pull the intake apart again to test for internal leaks, if that happens you best believe i will have 8 different injectors in my hand. I bought the injectors from ebay, the yellow ones. I probably should have went to southbay, they give a sh** about quality control. I don't think these other guys on ebay do. Southbay, would you want these pieces of junk? After i buy a set from you im going to just throw them away anyway...
Thank you for the offer however I'm going to pass on the injectors..
i'm sorry for all the problems you are having. When you are ready we'll be more than happy to help you
09-13-2015, 10:06 PM
