code p300 misfire & u1300 data 2 high voltage?

code p300 misfire & u1300 data 2 high voltage?

Postby lawbuck [OP] » July 8th 2008, 3:40am

vans been bucking at highway speeds with no light or codes. replaced crank sensor, throttle position switch, cam sensor, coil. a/c plugs wires cap rotor map sensor was replaced just before i bought it. it's an 01 4.3l vortec. now i'm gettin a code for po300 random misfires although not so random. acording to my tech 2 it's 1&4 cylinders and only between 1700-2800 rpm. although sometimes at idle. tried swaping plug wire around to see if anything changes nothing. pulled new a/c plugs all looks good there. egr valve cleaned and fuctioning. also just realized there is a code u1300 data 2 high voltage, what the hell is that. i'm lost. by the way i put a corvette servo in a couple weeks ago, what an improvment there. i also installed a k&n filter as well as a cat back custom 2.5" dual exhaust. please if anyone can help that would be appreciated.
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Re: code p300 misfire & u1300 data 2 high voltage?

Postby dcb » July 9th 2008, 2:47am

I have similar problems with my 2000 Astro. A stretched timing chain will cause the random misfire. A work around for this is to remove the distributer hold down bracket and file a slot in it so the distributer can be rotated counter clockwise about the diameter of the hold down bolt. This compensates for the slop in the timing chain and aligns the rotor with respect to the crank position sensor again. I did this to mine and and the random misfire stopped. However, I still have an issue getting mine to start after it sits a while. It may be the injectors, but I'm not sure. At the moment, I can crank it over until the battery runs down, and all it will do is chuckle occasionally. Any suggestions?
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Re: code p300 misfire & u1300 data 2 high voltage?

Postby lawbuck [OP] » July 10th 2008, 3:51am

i've replaced the distributor with an accel from summit racing, this seemed to help i can dial in to zero. still got misfires. unplugges mas air flow and misfire go away, replaced masss air flow and there back. if i unplug intake air temp sensor they go away, if i plug it in there back. pulling a po300 mifire code. wht the hell? i'm lost. by the way the teeth on the 200,000 mile distributor were so worn i couldn't believe it ran at all. if unplug those sensors the misfire go away but my original problem comes bak witch is jerk when driving down the road at highway speeds. my tech 2 scan tool says my timing is at 4degrees. i had it right @ 0 but seemed to be less responsive. also forgot to mention the new dist. body is billet insted plastic. someone help me solve this problem.
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Re: code p300 misfire & u1300 data 2 high voltage?

Postby jbichko » July 12th 2008, 6:53am

Fuel System - MIL ON/Rough Idle on Start-Up

File In Section: 06 - Engine/Propulsion System

Bulletin No.: 00-06-04-003B

Date: February, 2003

TECHNICAL

Subject:
Rough Idle After Start, And/Or A Service Engine Soon (SES) Light
(Unstick And Clean Central Sequential Fuel Injection (CSFI) Poppet
Valves or Convert to MFI)

Models:
1995-2002 Chevrolet and GMC S/T Models
1996-2002 Chevrolet and GMC C/K, M/L, G, P Models
1996-2001 Oldsmobile Bravada
1999-2000 Cadillac Escalade
with 4.3L, 5.0L or 5.7L Engine (VINS W, X, M, R - RPOs L35, LF6, L30, L31)
Except 2002 VIN X - RPO LU3 Models

This bulletin is being revised to update the Warranty Information. Please discard previous copies of Corporate Bulletin Number 00-06-04-003B with warranty chart (Section 06 - Engine). This copy is for Dealers in the state of CALIFORNIA ONLY.

Condition

Some customers may comment on rough idle after start-up, especially if the vehicle has sat overnight. These symptoms may be intermittent. The Service Engine Soon (SES) light may also be illuminated. Current misfire or history misfire codes may be detected with the Tech 2 scan tool.

Cause

A deposit build-up on the CSFI poppet valve ball and/or seat may cause the poppet ball to stick open or closed. In either case, the specific cylinder will be mis-fueled, resulting in a cylinder mis-fire condition.

Correction

A new injector unsticking and cleaning process has proven to be effective in restoring poppet valves to an "as new" condition. CSFI injector replacement should NOT be considered as a correction for this customer concern.

Check the vehicle history to determine if the vehicle is returning for a second fuel system repair for this condition. If the fuel system has been repaired for this condition previously, then inform the customer that an alternate fix is available. A new MFI fuel system has been developed that will back service the CSFI fuel system. The MFI fuel system eliminates the CSFI poppet valve ball and seat. The CSFI fuel system will need to be replaced as a unit. Refer to Central SFI to MFI Conversion instructions in this bulletin.

Notice : Individual CSFI injectors can not be replaced with MFI injectors. The entire CSFI fuel meter body will need to be replaced. The bracket used to retain the injectors in the fuel meter body is different between the CSFI and MFI unit. The unit may not seal if you mix injectors. Severe engine damage could result.

Cleaning the CSFI injectors is the preferred repair. The CSFI unit should not be replaced until cleaning has been attempted. If the vehicle should return for the same repair, then the CSFI unit can be replaced with an MFI unit. If the vehicle is out of warranty, the customer should be given the option of which fix to pursue.

Important : "GM of Canada" dealers require District Service Manager approval prior to replacing the CSFI unit with a MFI unit under warranty.

The first step of this process is to use the J 41413 Evap Pressure/Purge Station, in conjunction with the J 44466-10 pressure regulator/hose assembly, to provide the required high pressure (150 psi) source to perform the unsticking procedure. The J 39021 fuel injector tester and accessories provide the means to "energize" the injector. Some later model-year vehicles may utilize the Tech 2(R) to "energize" the injectors.

The second step of this process is to run the engine on a solution of 10% Top Engine Cleaner and 90% gasoline. This will effectively clean any deposits from the ball and seats of the poppets. It is very important that the engine fuel system is separated from the vehicle fuel system. Top Engine Cleaner may have detrimental effects on the fuel pump.

Parts Information





Cleaning Procedure Parts





CSFI to MFI Conversion Parts

Parts are currently available from GMSPO.

:D
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Re: code p300 misfire & u1300 data 2 high voltage?

Postby lawbuck [OP] » July 13th 2008, 1:51pm

after replacing damn near everthing on the outside of the engine that made sense to me i decided to give it a run 60+ mile on the highway. :naughty: didn't pound on it to bad. put it in passing gear a few times. got back to the shop and now i have a back rod knocking or spun bearings. :doh: so, i can get my hands on a 9,000 mile gm crate engine complete out a 99 truck its throttle body, :dance: he has harness and ecm. will this work? it would be my preference considering how that center point can be. if anyone know for sure this will work please let me know asap as i have a hold on this engine. thank guys i friggin love this site. :clap:
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Re: code p300 misfire & u1300 data 2 high voltage?

Postby lawbuck [OP] » July 29th 2008, 1:41am

i through a rod this passed week. check oil level as my press guage was rearding low. but my oil level was almost a quart over and smelled like fuel. so i bought an engine w/40k swaped every thing that was new from the old 199k engine. put new plugs wires. changed injection system to the upgraded mpi. now it runs fantastic except i get a surge or buck off and on witch is one of the first things it did when i bought it. but i replace d the crank sensor and it was gone. but here we go again. one of my customers said there's a good chance it could be the cat. any thoughts?
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Re: code p300 misfire & u1300 data 2 high voltage?

Postby gtkane » July 29th 2008, 2:40am

I doubt it's the cat...that usually results in a SERIOUS lack of power, not the problem you describe.
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