New Bucking User

Hi all, I'm new to this forum, but it has a lot of knowledgable users.
Most the info here is over my head, so I have a steep learning curve.

Hope it is OK to ask for help in this opening e-mail.
On Tuner Pro RT ver 5 (unregistered), how can I add Ignition timing advance and EGR state to the acquisition list so I can monitor those during driving? Also, how can I identify the ECM as site suggest my truck has 3-4 different ECMs? Tuner Pro RT shows PROM ID of 9025. I am using A179.ADX to acquire data, and can save log files. I did not load bin and xdf as I did not want to attempt tuning.
My goal is to fix my 1994 K1500, 4x4, TBI, 5.7L, manual 5 speed trans, which starts well but begins to run poorly after a couple of minutes. Any slight pressure on the accelerator causes it to buck and miss. Not trouble codes are set. If I let it set for 30 mins, it starts and runs fine no problems. Or if I keep babying it for an hour of driving, it slowly gets better. It only acts up the first start and run of the day.

I was hoping to use troubleshooting, and not shot-gunning the problem by replacing parts until is ran better. Maybe it is silly pride as I've spent more time thinking about it than parts would be worth.

if it's not in the adx file already, chances are you'll have to patch your bin file to replace other less important variable with the memory addresses of timing and egr duty cycle. this is a trivial operation if your xdf has been written well, but it does require acquiring some tuning gear....

if you wanted, a non-electrical solution to monitor EGR duty cycle would be to put a vacuum gauge in between the EGR solenoid and the EGR valve with a tee and run a peice of hose to your dash. you'll be able to see how much EGR duty cycle is commanded by the amount of vacuum applied to the valve vs actual engine vacuum.

on another note have you checked fuel pressure yet?

Quote:

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Originally Posted by steveo

if it's not in the adx file already, chances are you'll have to patch your bin file to replace other less important variable with the memory addresses of timing and egr duty cycle. this is a trivial operation if your xdf has been written well, but it does require acquiring some tuning gear....

if you wanted, a non-electrical solution to monitor EGR duty cycle would be to put a vacuum gauge in between the EGR solenoid and the EGR valve with a tee and run a peice of hose to your dash. you'll be able to see how much EGR duty cycle is commanded by the amount of vacuum applied to the valve vs actual engine vacuum.

on another note have you checked fuel pressure yet?

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It isn't in the ADX file, unfortunately. Possibly another close ADX file would work as it seems to be some leeway. I will have to try the 'manual method' otherwise.
I could not see how to connect my Schrader valve pressure gauge to the nut and rule line on the rear of the TBI, so I skipped that step. I saw an adaptor someplace, but not on hand.

But I followed up on your 'do the basics' message, and the rotor and cap, though only have 20K miles on them, are severely corroded, and the button on the inside cap had turned to crumbs. Looked like somebody was welding inside the rotor! The plugs also were bad on one side. I assume it is the side pointing to one of the valves. It was not oil, but something that is whitish crumble powder going from the electrode over to the threads or ground. Ethanol reaction?? Wires look and ohm out good. So I'll reply back with the new cap, rotor and plugs.

wear in the rest of your ignition system, weak coil, gaps funky on spark plugs, burned coil wires.. that takes your cap n rotor out pretty quick.

that white powdery crumbly stuff on your plugs can be due to detonation and excess combustion heat from running lean so i'd still check fuel pressure... and if spark is severly inhibited by it that would explain your distributor burning up quickly.

unforuntately tbi is a total pain in the ass to check fuel pressure, it does require you to buy or make an inline adaptor. but another way is to take an old fuel filter, and tap and drill a fitting or something into it for your pressure tester...

Well, my truck is back to running now with new plugs and distr parts. Strange, the spring loaded button inside the top of the cap looked like a small mushroom, and when I touched it to see if it was springy, it crumbled to dust!

Just to note I also found the warm air diverter in the air filter opening would only open half way when warmed up, and three vacuum hoses that were split or gnawed thru, and the normally sealed and unused port on the charcoal canister blew off, allowing unfiltered air in. It is a separate topic, but with modern closed loop system, the ECU will still try to maintain the correct fuel/air ratio if there is an extraneous leak? The truck has a MAP sensor, but no MAF sensor.
I will check my fuel pressure, and thanks for the info.