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Old 12-07-2009, 02:24 PM   #1
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RPM range problems - Updated with error codes

I have a 1991 H.O motor with aluminum heads, longtube headers, F303 cam, typhoon upper and lower intake, and msd (dizzy,coil,6AL box) and 5speed transmission. For some reason i can not go past 3500 rpms, what could be the cause of this and what can I do to fix this problem?
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Old 12-07-2009, 03:05 PM   #2
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Re: RPM range problems

what does it do at 3500 rpms? sputters, does it act like a rev cut off (rev limit) etc?
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Old 12-07-2009, 03:14 PM   #3
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Re: RPM range problems

it starts to sputter, sounds like i miss shift when it gets to 3500
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Old 12-07-2009, 04:17 PM   #4
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Re: RPM range problems

have you checked timing, and made sure all cylinders are firing?
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Old 12-07-2009, 04:22 PM   #5
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Re: RPM range problems

i had my timing done. i need to run the codes while the car is running and see what comes up, and like you said check and see if all the cylinders are firing... how can i do that?
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Old 02-10-2010, 12:16 PM   #6
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Could my msd 6AL box be the problem????

I have a 1991 H.O motor with aluminum heads, longtube headers, F303 cam, typhoon upper and lower intake, and msd (dizzy,coil,6AL box) and 5speed transmission. For some reason i can not go past 3500 rpms, what could be the cause of this and what can I do to fix this problem? I just replaced my fuel regulator because a few people said i might not be getting the right pressure, so i changed it to a holley adjustable one and the problem is still there... So now i am wondering if it is more of a ign problem. So now i am wondering if it could be my msd box what do you think?
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Old 02-10-2010, 12:34 PM   #7
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Re: Could my msd 6AL box be the problem????

isnt there a little thing you can put in the box to set rev limiter~ make sure its not set at 3500
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Old 02-10-2010, 12:40 PM   #8
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Re: Could my msd 6AL box be the problem????

i will double check the chip that is in the msd box and make sure it isnt anything small
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Old 02-10-2010, 03:58 PM   #9
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Re: Could my msd 6AL box be the problem????

also try a diff chip if you have one, the one in there might be messed up~
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Old 02-10-2010, 05:01 PM   #10
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Re: Could my msd 6AL box be the problem????

first off that box do you have? If you think your rev limiter is kicking in remove the chip completely.

can you rev the engine past 350RPMs seating still?
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Old 02-10-2010, 07:36 PM   #11
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Re: Could my msd 6AL box be the problem????

Def check the chip
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Old 03-15-2010, 01:02 PM   #12
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Error codes

Right now I am having problems with my car... Right now i can not go over 3500 rpms... When i reach that it starts to tach out... I ran my codes with the key in the on position and 81,82,85,84,22,33 and 95 came up. I also ran the codes with the car running and 33,94 and 44 came up. I know some of these are smog codes and i am running long tube headers but for the others, what are the specifics that i need to do to get these to go away?
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Old 03-15-2010, 07:33 PM   #13
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Re: RPM range problems - Updated with error codes

I am running mostly off the top of my head so I can't guarantee any accuracy but..

81 and 82 are smog pump related, that's not an issue

84 is EGR - Do you have yours blocked off entirely?

I believe 85 is canister purge valve

22 and 33 is throttle position sensor, That could be a biggie, that would be worth testing - I can't recall which wire was which off the top of my head so I'd have to dig a little if you need a pinpoint test.. I would say this could be a big deal



22... Is coolant temp sensor out of range I believe.. no big deal there

95 if I remember right is fuel pump circuit.. High resistance or bad ground on your fuel pump circuit would cause the lack of revving, too

BEST WAY TO CHECK is to skip the swapping out of parts.. attach a fuel gauge and check the fuel pressure, at idle and under load..

94 is torque converter.. doubt you have that problem
44 is air injection..

Basically.. look at your fuel pump (FIRST) and your TPS second..
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Old 03-15-2010, 08:17 PM   #14
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Re: RPM range problems - Updated with error codes

ok thanks, i will check those things
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Old 03-17-2010, 11:13 AM   #15
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Re: RPM range problems - Updated with error codes

How can i fix code 95 "fuel pump secondary circuit fault"?
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Old 03-18-2010, 12:38 AM   #16
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Re: RPM range problems - Updated with error codes

Hmm... I really wish I could tell you off the top of my head, I haven't been a ford tech for 3-4 years now... Secondary circuit means the circuit that is controlled by the primary circuit..

So the primary circuit controls the relay which controls the pump...

The ECM (the 9AL is great for adapting to mods but it's ancient in terms of diagnostics) thinks that the wiring from power source to ground for the fuel pump has either a short on the power side of the circuit, or high resistance on the ground..

Best way to check, is to check for available voltage to the pump using a DVOM

If you have approx 12.6 volts to the pump, check voltage drop, with the car running (IE fuel pump is running) it should drop approx 12-14 volts across the pump.. If not, something else is using the voltage available to the circuit..
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Old 03-18-2010, 10:04 AM   #17
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Re: RPM range problems - Updated with error codes

thanks, I will check the voltage on that and see what it reads, maybe should I also try a new relay?
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Old 03-18-2010, 06:41 PM   #18
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Re: RPM range problems - Updated with error codes

Relay shouldn't be a problem, that would be the item that allows power to pass through the secondary circuit - If the fuel pump is coming on, I doubt that would be the problem..

Honestly, start with hooking a fuel pressure gauge up to the fuel rail.. see what your pressure is like, your fuel pump could be fine
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Old 03-23-2010, 10:57 AM   #19
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Re: RPM range problems - Updated with error codes

Thanks to everybody who helped me with coming out with things to check, but i got the car working fine now. I ended up being a wire that went to my starter solenoid that was on the wrong post. I called the tech support of the maker of my efi swap harness and told me a wire that went to my starter solenoid needed to be on a post that only was hot when the key was in crank position and i had it on a post that was hot all the time. So now for a tune, does anyone know of any good places in the bay area?
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Old 03-23-2010, 11:40 AM   #20
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Re: RPM range problems - Updated with error codes

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Old 03-25-2010, 06:07 PM   #21
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Re: RPM range problems - Updated with error codes

thanks for the info...
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