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12-09-2014, 09:14 PM | #1 |
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Join Date: Apr 2007
Location: Virginia
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Need TBI troubleshooting help
Hi guys,
First a little background on the truck 1988 V30 (1 Ton 4x4 Dump Truck, manual tranny, TBI 350) This is the mountain neighborhood plow truck and never goes off our private roads. I did a complete rebuild of this truck this fall, all major systems and sensors are new, to include: Rebuilt stock TBI Long tube headers with heated O2 sensor Coolant temp sensor IAC Oil pressure sensor MAP TPS EGR Valve EGR Solenoid Speedway Motors TBI wiring harness Distributor (stock replacement) Ignition Coil Plugs/wires Fuel pump Here's the problem. Truck starts and runs/idles pretty well. It does have a delay/say when you open the throttle. I have all the vacuum lines capped at the TBI except for the PCV port and MAP port. The only sensor I have not changed is the ESC module, but one is on the way. When I check the timing (using the correct method by unplugging the timing wire), it runs very very rough and will cut out at 0 degrees. It only idles smooth at a ridiculous amount of advance, that is off the indicator plate. It will run decent at about 8 degrees advanced, but anything close to 0 gets a rough idle. If I unplug the ESC module, there is no noticeable difference in anything. Is that normal? Also, the EGR valve doesn't seem to be doing anything. Normal? When I run a scan, I get about 6 codes, relating to EST, Coolant temp sensor, inlet air temp, etc...but I'm not sure how accurate this is. There is a TON of vacuum at idle on the PCV port. It runs pretty good at that advanced timing, but with all the codes and the sag/hesitation when you open throttle, I am assuming there is an issue and better performance to be had. Any ideas? Thanks in advance!
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Maj USAF 71 K5 Blazer CST 72 K20 HT383 NV4500 Mass-Flo EFI 71 K10 LWB 52 Dodge Power Wagon 67 Dodge WM300 Power Wagon 48 Dodge WDX Power Wagon My Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=239487 |
12-10-2014, 04:14 PM | #2 |
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Join Date: Mar 2008
Location: williamsport,pa
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Re: Need TBI troubleshooting help
is it the original engine for the truck? maybe the outer ring of the balancer spun.
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12-10-2014, 05:07 PM | #3 |
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Location: Virginia
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Re: Need TBI troubleshooting help
That's certainly possible. I don't know much other than the previous owner said the engine was rebuilt about 10K miles before I bought it.
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Maj USAF 71 K5 Blazer CST 72 K20 HT383 NV4500 Mass-Flo EFI 71 K10 LWB 52 Dodge Power Wagon 67 Dodge WM300 Power Wagon 48 Dodge WDX Power Wagon My Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=239487 |
12-11-2014, 09:47 AM | #4 |
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Location: Ocean Springs, MS
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Re: Need TBI troubleshooting help
How did it run before you replaced all that stuff? Do you have a laptop you can connect to it?
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Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100 |
12-11-2014, 09:55 AM | #5 |
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Re: Need TBI troubleshooting help
Well when I got it it ran like crap and had all sorts of issues. So I basically did a complete rebuild of the entire truck. All major systems are brand new. It runs a million times better than it did and the initial road tests show no symptoms. It's just that the timing indicator on the harmonic balancer is about 2 inches before the timing tab even starts!
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Maj USAF 71 K5 Blazer CST 72 K20 HT383 NV4500 Mass-Flo EFI 71 K10 LWB 52 Dodge Power Wagon 67 Dodge WM300 Power Wagon 48 Dodge WDX Power Wagon My Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=239487 |
12-11-2014, 09:55 AM | #6 |
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Re: Need TBI troubleshooting help
I can connect it to a laptop. Are you referring to WINADL or something like that? Will it tell me exactly what the timing is set at?
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Maj USAF 71 K5 Blazer CST 72 K20 HT383 NV4500 Mass-Flo EFI 71 K10 LWB 52 Dodge Power Wagon 67 Dodge WM300 Power Wagon 48 Dodge WDX Power Wagon My Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=239487 |
12-11-2014, 01:50 PM | #7 | |
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Location: Orlando Florida
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Re: Need TBI troubleshooting help
Find TDC and see if the marks line up. Mine didn't have the timing tab and the one I put on was wrong, so I made my own mark to use the wrong tab.
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12-11-2014, 06:33 PM | #8 |
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Re: Need TBI troubleshooting help
Yes, Winaldl is a a good program. It will tell you how much advance the ECM is adding to base timing, but not what the base timing is. To establish that, you verify your marks are correct, disconnect the set timing connector behind the master cylinder, and set timing using a light to 0 degrees. The aldl program will also be able to show you what the sensors on the engine are reading.
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Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100 |
12-11-2014, 07:27 PM | #9 | ||
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Re: Need TBI troubleshooting help
Quote:
Quote:
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Maj USAF 71 K5 Blazer CST 72 K20 HT383 NV4500 Mass-Flo EFI 71 K10 LWB 52 Dodge Power Wagon 67 Dodge WM300 Power Wagon 48 Dodge WDX Power Wagon My Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=239487 |
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12-12-2014, 10:30 AM | #10 |
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Re: Need TBI troubleshooting help
Yes, the idle should be advanced when the timing connector is reattached, but it should be more than 4 degrees. Does it advance further if the engine is revved? No idea why it would not want to re-start.
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Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100 |
12-12-2014, 08:49 PM | #11 |
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Location: Guntersville Alabama
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Re: Need TBI troubleshooting help
Just a note , I did not see if you replaced the cam in the rebuild . I did a rebuild and installed a little different cam and I could not get it to run worth a crap . I tried every thing . I finally threw the timing light on the ground and started cranking on the distributor until I found the sweet spot. It run like a champ after that. I think I was running about 12*. The cam I put in did not like the stock setting at all. Is it possible that a different cam has been installed. Something to think about. Good luck.
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