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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 12752
Experience:  Have owned a repair shop for 25 yrs.
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95 chevy: TBI..raining..puddle..which made the truck run very rough

Resolved Question:

'95 Chev c1500 4.3 TBI, with a 5 speed trans. While raining last week I hit a big water puddle which made the truck run very rough. Now it does run,but, I need to very lightly press the gas to get the rpm's up to about 2000 to to get going, and then when I shift it really misses and stumbles, sometimes backfiring. Then when I get up to 50 mph or so on flat straight road for a short distance, with steady throttle it will start losing power and if I press the gas, just very easy, it will not pick back up. I have so far changed the plugs, none were wet or fouled just dry with a light brown color, plug wires, distributor, rotor, control module. It has a fairly new battery, and I made sure of a tight connection there. I've sprayed carb cleaner around the various vacuum lines with no change.
Thanks for any help...
Jesse
Submitted: 2 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 2 years ago.

hi

sense the problem began after hitting water..the problem may be the ignition coil...the water could have caused the coil to crack,,it may be a hair line crack and may not be able to see it

thanks

Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 12752
Experience: Have owned a repair shop for 25 yrs.
Tim's Auto Repair and 7 other Chevy Specialists are ready to help you
Customer: replied 2 years ago.
Hi, thanks for the answer, and please let me go get a new coil to try. I'll accept the answer and will let you know when it's changed. If (just if) I need more help with this I would like to keep the line open till this is solved ok?
Expert:  Tim's Auto Repair replied 2 years ago.

yes

that will be fine

thanks

 

Customer: replied 2 years ago.
Hi...new coil installed, no change in running. Need more ideas.
Thanks
Expert:  Tim's Auto Repair replied 2 years ago.

ok

lets unplug the vacuum line from the egr valve....unplug it and put a screw or something in the vacuum line to block the vacuum.....let me know if that makes a difference

Customer: replied 2 years ago.
tried but no change. Just to confirm the egr is the round metal frame unit that is by the distributor side of the manifold
Expert:  Tim's Auto Repair replied 2 years ago.

yes..

ok...does the engine light stay on?if so,,can you give me the trouble codes?

Customer: replied 2 years ago.
the check engine light will come on and go off while driving. How do I get the codes to show up?
Expert:  Tim's Auto Repair replied 2 years ago.

ok

lets do this

1995 Chevy Truck C 1500 Truck 2WD V6-262 4.3L VIN Z TBI
Computers and Control Systems Testing and Inspection, Reading and Clearing Diagnostic Trouble Codes: Reading Diagnostic Trouble Codes, Without Scan Tool
70_gma91cec604-102.pngALDL Connector (Located Underdash)



READING DIAGNOSTIC TROUBLE CODES:
The means of communicating with the control module is the Data Link Connector (DLC) located under the instrument panel and is sometimes covered by a plastic cover labeled "DIAGNOSTIC CONNECTOR." The DLC is used in the assembly plant to receive engine information to determine proper operation before it leaves the plant. The Diagnostic Trouble Codes (DTC's) stored in the control module memory can be displayed by counting the number of flashes of the Malfunction Indicator Lamp (MIL) (Service Engine Soon) when the diagnostic terminal of the DLC is grounded. The DLC terminal "B" (diagnostic terminal) is the second terminal from the right of the DLC top row. The terminal is most easily grounded by connecting it to terminal "A" (internal control module ground), which is located to the right of terminal "B" on the top row of the DLC.

When terminals "A" and "B" have been connected, the ignition switch must be turned to the "ON" position with the engine NOT operating. The MIL (Service Engine Soon) should flash DTC 12 three times consecutively. This would be the following flash sequence: One flash, pause, two flashes, long pause, one flash, pause, two flashes, long pause, one flash, pause, two flashes. DTC 12 indicates that the control module diagnostic system is operating properly. If DTC 12 is NOT indicated, a fault is present within the diagnostic system itself, and should be addressed by consulting the appropriate diagnostic chart.

Following the output of DTC 12, the MIL will indicate any DTC three times consecutively. However if no other codes are present will continue to repeat DTC 12. If more than one diagnostic trouble code has been stored in the control module memory, the DTC's will be displayed from the lowest to the highest with each DTC being displayed three times.

DIAGNOSTIC MODE:
When the diagnostic terminal is grounded with the ignition "ON" and the engine "OFF," the system will enter the diagnostic mode. In this mode, the control module will:

- Display a Diagnostic Trouble Code (DTC) 12 by flashing the Malfunction Indicator Lamp (MIL) "Service Engine Soon" (indicating that the system is operating properly).

- Display any stored DTC's by flashing the Malfunction Indicator Lamp (MIL) "Service Engine Soon." Each DTC will be flashed three times, then DTC will be flashed again.

- Energize all control module controlled relays and solenoids except the fuel pump relay. This allows checking circuits which may be difficult to energize without driving the vehicle and being under particular operating conditions.

- Move the Idle Air Control (IAC) valve to its fully extended position on most models, blocking the idle air passage. This is useful in checking the minimum idle speed.

FIELD SERVICE MODE:
If the diagnostic terminal is grounded with the engine running, the system will enter the "Field Service" mode.

In this mode, the MIL "SERVICE ENGINE SOON" light will indicate whether the system is in OPEN or CLOSED LOOP operation.

If the system is in OPEN LOOP operation, the light will flash approximately two and one-half times per second.

CLOSED LOOP operation is indicated by the light flashing approximately once per second. Also, in "CLOSED LOOP" the light will stay "OFF" most of the time if the system is running lean. It will stay "ON" most of the time if the system is running rich.

While the system is in the "Field Service" mode, new codes cannot be stored in the control module and the "CLOSED LOOP" timer is bypassed.

Customer: replied 2 years ago.
it just kept flashing the DCT12 code 1flash pause 2 flash long pause, over and over (more than 3 times)
Expert:  Tim's Auto Repair replied 2 years ago.

ok

there is no codes stored,,strange........

check the vacuum line to the map sensor,,,make sure it is connected and has a vacuum on it

Customer: replied 2 years ago.
that has good vac. that is the one on the passenger side hanging over the valve cover...I also checked the vac on the evap can and that was very slight, does it not need as much vac.?
Expert:  Tim's Auto Repair replied 2 years ago.

sorry had computer trouble here..

tell me..does it blow any black smoke out the exhaust?

does it do this with the engine cold and hot?

Customer: replied 2 years ago.
I haven't noticed any black smoke, and it don't matter if it's cold or warm. Sometimes when I push around on the plug wires and coil wire at the dist., then start it, it will run batter for just a bit then be back where it was. Also I changed the TPS (I know it's not part of the ign. system, but...) and took the exhaust pipe apart between the cat and muffler, and had pressure exhaust there but not so much at the tailpipe end, could the muffler be blocking exhaust to make it do this?
Expert:  Tim's Auto Repair replied 2 years ago.

well

yes,,a clocgged muffler could cause this,,,but the engine would be really quiet if this is the case...i am thinking your problem may be the pick-up coil inside the distributer,if this is the case,you may just want to replace the complete distributer with a new rebuilt unit,sense the distributer will need to come out and apart to replace the pick-up

thanks

graphic

Customer: replied 2 years ago.
OK...one more trip to the parts joint. I'll let you know tomorrow or Monday how it worked...
Thanks
Expert:  Tim's Auto Repair replied 2 years ago.

ok

you are running out of possibilities here

Customer: replied 2 years ago.
OK...got the new dist. in and it runs better, but where is the timing tab at to set timing?
Thanks...
Expert:  Tim's Auto Repair replied 2 years ago.

ok

well.if it isnt broken off..it should be on the timing cover

thanks

 

1995 Chevy Truck C 1500 Truck 2WD V6-262 4.3L VIN Z TBI
Ignition Timing Adjustments: Ignition Timing Adjustment
WARNING: To prevent possible personal injury from a moving vehicle or operating engine, do the following before performing the checks:

^ Engage the parking brake and block the wheels.
^ Place the transmission in neutral.


1. Refer to the Vehicle Emissions Control Information label under the hood. Always follow the Vehicle Emissions Control Information label procedures first before using the following procedure.

2. Put the IC system in the bypass mode by disconnecting the "set timing" connector. This is a single wire sealed connector that has a tan with black stripe lead. This connector breaks out of the wiring harness below the heater case in the passenger compartment.

3. With the ignition switch "OFF," connect the pickup lead of the timing light to the number one spark plug. Use a jumper lead between the wire and plug or an inductive type pickup.

DO NOT pierce the wire or attempt to insert a wire between the boot and the wire. Connect the timing light power leads according to manufacturer's instructions.

4. Start the engine, and aim the timing light at the timing mark. The line on the balancer or pulley will line up at the timing mark. The timing should be O° TDC. If a change is necessary, loosen the distributor hold-down clamp bolt at the base of the distributor. While observing the mark with the timing light, slightly rotate the distributor until the line indicates the correct timing. Tighten the hold-down bolt, and recheck the timing.

5. Turn "OFF" the engine and remove the timing light. Reconnect the number one spark plug wire, if removed.

6. Reconnect the "Set Timing" connector.

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