Running lean with Bosch III
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Joined: Mar 2008
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From: nj
Car: 89 iroc
Engine: l98
Transmission: tremec
Re: Running lean with Bosch III
i run them in two of my cars.. always 130+- a few on the BLM. if its 160 plus the computer won't add fuel. but under 160 it will.. a high blm just tells you the computer is adding fuel for a particular point on the VE. i would not worry about it.
Re: Running lean with Bosch III
When you buy injectors from me, FIC and some others they are flow balanced.
THe accel set wasn't. In fact, are you SURE the old injectors were 24s? Flow them to make sure. MOST, and I say MOST of the Accel I see are 30 lbs. It's rare to see a 24.
Could be they were off as much as 10%. The best thing to do is flow the Accel injectors see where you were at and if there were any problems with them.
THe accel set wasn't. In fact, are you SURE the old injectors were 24s? Flow them to make sure. MOST, and I say MOST of the Accel I see are 30 lbs. It's rare to see a 24.
Could be they were off as much as 10%. The best thing to do is flow the Accel injectors see where you were at and if there were any problems with them.
Last edited by InjectorsPlus; Nov 29, 2010 at 06:01 PM.
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Joined: Oct 2000
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From: amanda ,ohio,usa
Car: 1989 camaro
Engine: 355 tpi
Transmission: 700r
Axle/Gears: 3.50
Re: Running lean with Bosch III
I pretty much had the same thing happen with me, with 24 accells I could keep my pe@RPM very close to stock chip, but put bosch III's 27's in car and had to add over 50 to my pe in upper rpm's. maybe its like he said the accells dont flow what they say.
Re: Running lean with Bosch III
I didn't flow them. But I've got the box the injectors came in with the part number. And they are 24# 85-93 injectors part number 150824. On my 89 with the L98, the injectors should be 22#. Though I've seen 21.5# mentioned. So, 24# is too big of an injector. Which is why it would carbon foul plugs. The set of old spark plugs, the PO gave me were carbon fouled. I had a high speed miss, I replaced the spark plugs. They were carbon fouled and that fixed the high speed miss.
I'm just sayin.. doesn't seem right I know FIC does what we do and flows them before they go out. Could be FIC sent the wrong ones? Who knows. But I would believe one of my injectors over an Accel OEM injector (I'm sure FIC would say the same) every day of the week.
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Re: Running lean with Bosch III
Just curious why you'd think the Accel would be boxed wrong? They ran rich like you'd expect running 24# instead of 22#. For whatever reason the PO put in 24# instead of 22#. But the Accel 24# hung closer to 128 than the Bosch III at stock pressure. I think the reason the Accel didn't run richer than they were was because my running pressure was low normal of 34. Where some guys run at 39. The only reason why I replaced injectors is because it was running rich because the PO put in 24# injectors instead of 22#.
If I understand right, you were running the 24s at 34 lbs of pressure and the 22s at 55 and still had a problem? Something doesn't seem right there. Is is possible the car has a cam, heads, port work or something that you don't know about?
The only thing I pretty much care about is that I don't burn my engine up. If I can get my BLM's to hang close to 128, then that should be fine.
[/quote]The way I understand it is the Bosch III work differently than the OEM injector. So that it could throw things off which is why some recommend to get a tune when replacing the injectors with a new style injector meant for a different engine.[/QUOTE]
Yes, they are different in both design or application. But flow is flow. Regardless of HOW the fuel is delivered.
The differences between the old style and Bosch III are the locations of the coil. The BoschIII do work differently, they do not use gasoline to run over the coil and cool it. This wears the coating off the coil over time, then they fail. The B3 don't have this problem/
Re: Running lean with Bosch III
I was running the Accel 24# at 34 psi. As that is what it ran with the stock pressure. I put in the Bosch III 22#, and it ran lean at 34 psi. So, I put in an adjustable FPR and raised the running pressure to 41. Which calculates both should be flowing the same with 22# at 41 psi, and 24# at 34 psi. But for some reason, I still ran lean with the Bosch III. Where as it ran rich with the Accel. So, something does sound off. But the Accel ran rich as would be expected. And others have reported running lean with the Bosch III. So, I'd lean to the Bosch III with what ever it may be. Some don't have a problem with the Bosch III running lean.
I did raise the running pressure to 47 and that brought the INT and BLM to 130. But I haven't done any driving around scans to see what the BLM does while driving around. If I can get it close to 128. Then that will be fine. If not, I'll see if I can get some Bosch III at 23#. If not, maybe try the Bosch II.
See how the 47lbs works, if that's good, you'll be fine. But because you had 34 lbs of pressure on the stock regulator, you may have had another problem.
It's getting late and all those numbers and #### signs are confusing me..
Re: Running lean with Bosch III
I don't think I've heard anyone post their L98 running at 43.5 psi stock. Its always in the mid to late 30's. The highest I've heard is 41. When you take the vacuum off the FPR, the book says you should see a pressure of 40.5-47 psi. Then when you connect the vac line the pressure will drop 3-10 psi.
So, that's why Haynes says a normal running pressure of 34-39.
My pressure with the vac line off stock is 41. So, that's in range. With the vac line connected, it drops to 34. Which also is in range as that is a 7 psi drop. It's low normal. Lots of others run the same stock pressure as mine. Some run mid to high normal.
So, that's why Haynes says a normal running pressure of 34-39.
My pressure with the vac line off stock is 41. So, that's in range. With the vac line connected, it drops to 34. Which also is in range as that is a 7 psi drop. It's low normal. Lots of others run the same stock pressure as mine. Some run mid to high normal.
Re: Running lean with Bosch III
I believe the 40.5-47 range with FPR disconnected and the 3-7 psi drop with FPR connected come from the FSM. I've seen probably around 20 posts of people with L98's posting their running fuel pressure. The highest was 41. But mostly in the mid to late 30's. That pressure range above is what everyone says on the Corvette Forum it should be at. So, I'm in range stock.
Again, Stock FP is 43.5.
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Re: Running lean with Bosch III
Set it with the vacuum disconnected, if the car is running. If you follow your flowchart you'll see that is referenced in there, because they specify a pressure of 40.5-47psi (average of that is 43.75psi... that should give you a clue that the stock setting is 43.5 as mentioned above) key on engine off (while its priming, no vacuum).
The 'running pressure' you're referring to is just to see if the FPR is working or not, the number itself is kind of irrelevant unless you want to back engineer the FPR.
The 'running pressure' you're referring to is just to see if the FPR is working or not, the number itself is kind of irrelevant unless you want to back engineer the FPR.
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Re: Running lean with Bosch III
Yep, and the number with it connected, as I mentioned, is kind of irrelevant to most everyone. That is probably where the confusion comes from, most people never refer to that number as it can vary depending on what your engine vacuum is at idle.
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