IROC-JP

After I put in an AFPR, shift kit, and b&m megashifter my car vibrates to the point where it looks like I have the shakes when sitting inside. I though maybe the fuel pressure was too high at 48 psi so I backed it down to 43 psi, but it still vibrates. Once the engine is over 1500 rpms everything is fine but at idle it shakes like crazy. It seems like it is a rough idle, but what is causing this?

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305 TPI
Edelbrock headers, highflow cat, borla cat-back exhaust, AFPR, modified MAF,
Stage 2 chip, 1.6 ratio roller tip rockers, b&m megashifter

snakeskinner

I would look for a vacuum leak from installing the AFPR. possibly a hose or a runner/plenum gasket. Kyle

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Kyle Osterholt
Okarche, Oklahoma
ASE Master Certified
86 T/A 383 TPI
89 TTA #1002 T-top/Leather
89 TTA #1358 Hardtop/Leather
80 T/A Pace Car
73 Opel GT

IROC-JP

I have checked all the hose and the runner to plenum bolts, but it still seems to be idling rough, in fact it rattles the exhaust like mad, so now I have a small leak in the exhaust just above the cat. The only other info can give is that when the engine idles the fuel pressure is about 43 psi, but when I just turn the engine off, the fuel pressure is about 50 psi. Is that normal?
Please help, this is driving me nuts.



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305 TPI
Edelbrock headers, highflow cat, borla cat-back exhaust, AFPR, modified MAF,
Stage 2 chip, 1.6 ratio roller tip rockers, b&m megashifter

snakeskinner

can't say for sure without laying my hands on it. I wouldn't worry about the pressure because when you shut the engine off, you lose vacuum in the manifold and to the fuel pressure regulator which means your pressure goes to what you set it at (you should be setting pressure with the hose disconnected). The pump will continue to run until the oil pressure drops low enough to shut the switch to the pump off. This will make your pressure do as it is doing. As far as the rough idle, might be time to get someone with more experience to help you out, Kyle

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Kyle Osterholt
Okarche, Oklahoma
ASE Master Certified
86 T/A 383 TPI
89 TTA #1002 T-top/Leather
89 TTA #1358 Hardtop/Leather
80 T/A Pace Car
73 Opel GT

IROC-JP

Thanx for the advice. So I should disconnect the hose to AFPR while the engine is running inorder to get an accurate pressure reading?
Thanx for help, Jason

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305 TPI
Edelbrock headers, highflow cat, borla cat-back exhaust, AFPR, modified MAF,
Stage 2 chip, 1.6 ratio roller tip rockers, b&m megashifter

CamaroZ_85

Do you have a misfire?? that tends to smooth out a bit as the rpms climb....just another thing to look for

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350, Comp 262, Edelbrock Performer intake 600 cfm carb and exhaust, headers

IROC-JP

How do I check for a misfire? Should I check to see if the spark plugs are all firing?

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305 TPI
Edelbrock headers, highflow cat, borla cat-back exhaust, AFPR, modified MAF,
Stage 2 chip, 1.6 ratio roller tip rockers, b&m megashifter

snakeskinner

setting fuel pressure varies between the type of engine. Ours are all set with the vacuum removed. You are actually setting the WOT pressure because under hard acceleration, your vacuum goes to zero. Kyle

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Kyle Osterholt
Okarche, Oklahoma
ASE Master Certified
86 T/A 383 TPI
89 TTA #1002 T-top/Leather
89 TTA #1358 Hardtop/Leather
80 T/A Pace Car
73 Opel GT

badbird88

Correct me if I'm wrong but can't a bad install of a shift kit cause idling problems?
Who installed the shift kit? Was there any drilling required or just a simple replacing of parts? Just another thought no one else has mentioned. As far as the misfire here are a few ways to check for this.

First make sure all your wires are in the proper firing order on the distributer. Any manual will show you the order. Check the wires for broken/burnt areas like where they have touched the exhaust. I even had some wires burn out where the connector is clamped onto the wire (cutting and making your own wires but possible with already made wires). You can usually look into the boot and see the burnt pieces if they are. I even had one boot just break off in my hands when I was pulling on the wire.

Another way is to pull all the wires off the distributer cap and push them back on but not to the point of where they are down all the way. This way you can crank the car up and one at a time pull the wires off enough to see if they are firing, then push them back on. You want have to pull them off very far to see a nice blue arc sparking across the wire and the electrode on the cap. One important thing to do before you start grabbing wires while it's running is get a pair of long handled pliers with good rubber grips on them and keep your hand as far away from the metal of the pliers as possible. That spark will jump across the rubber boot and onto the pliers and then pop the fire out of you! It's not a fun experience..kind of like a dog geting poped by an electric fence when he's wet.. ! Where rubber/leather gloves also if you want to be even more careful but don't trust them to stop the spark. I can't stress this point enough and you will know why if you get shocked by that freaking spark!

Pulling the plugs is a good way to see if they are all firing and you can diagnose other problems by how they look, but man if I'm going to waste my time pulling plugs I'm going to change them at the same time!

Do you get any codes being set during all the bad idling? It could be a vacumn leak like everyone else has been stating.

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1988 TA 300+hp 350 w/ TBI and Holley TB unit, Holley projection intake,
WC T-5, 3.42 gears w/ Auburn posi. MSD 6A, edelbrock TES headers, dynomax 3" cat and cat-back system, ACCEL coil, polyurethane bushings all around, aluminum driveshaft, Mr. Gasket open air cleaner.

1993 S-10 w/ 4.3L V6 TBI, slightly bigger cam, Mild polish job and 3 angle valve job on heads, Edlebrock TES headers, Dynomax cat back, MSD 6A, ADS chip

2000 Kawasaki KX 125

IROC-JP

I did install a shift kit by b&m that involved drilling some holes. However my trans must have had some modifications because some of the holes were already drilled out. And I wasn't able to modify the 1-2 or 3-4 accumulator because it was missing one piston pin and the pistons were reversed on the instructions, so I was confused and did not mess with that part.

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305 TPI
Edelbrock headers, highflow cat, borla cat-back exhaust, AFPR, modified MAF,
Stage 2 chip, 1.6 ratio roller tip rockers, b&m megashifter

84IROC

Readjust the fuel pressure with the hose disconnected and plugged to 43psi, then with the hose hooked back up it should be around 35 psi. Now clear the computer by removing the fuse from its power source for 2 minutes. Next, take the vehicle out and drive it for 30 minutes without extended periods of idling to allow the ECM to readjust its fuel maps that were skewed when you were running way too high a fuel pressure and the ECM was being sent all kinds of bogus info from the 02 sensor.

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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!

fbodyking

Didn't the Beach Boys sing a song called Bad Vibrations?