slow starts, TPS codes, CEL set ... my fault, or just one of those things? sorry, wrong forum!

working on it · September 25, 2024

I was prepping my '04 Chevy 2500HD for the yearly inspection/emissions test (tomorrow), and noticed that the engine was slow to start, when I first moved it to where I was going to wash it. It started quicker, on the second and third tries, but still was a bit slow.

I washed the truck (1.5 hours effort), then I was going to back it into its' normal parking spot, and once again, it started up grudgingly, so I got out my Clore 20-amp smart charger, and my Innova 3100i scan tool (with battery/alternator tester). The battery is always on a 1.5 amp Duralast charger/maintainer, so I expected the battery to be nearly charged, and it was. The Clore said it had a 95% charge to start, and after 10 minutes it reached 100%. I used the Innova scan tool to test both the the battery and alternator...both were good. So, why the slow start?

I then tried restarting it, and suddenly the CEL came on (TPS malfunction codes on both generic OBD2 and Chevrolet Enhanced readouts. The DIC said that engine power was reduced (it was, severely, with absolutely no accelerator pedal response, at all). So, I had no choice than to clear the codes, just to unblock the driveway (I surely didn't want to, because the emission monitors now said "incomplete", and I was planning to get the inspection tomorrow).

After cleaning-up, I decided to try running the "drive cycle", hoping to clear the "incomplete" monitors; I was able to get all but the "evap" monitor to complete (good enough for the inspection, in Texas), and while I was driving it (40 minutes), I was impressed with the throttle response, considering that the TPS set a CEL. Hopefully, the truck will start and run OK for the inspection (once started, I won't shut it off); if the CEL pops-up later, then I'll have some time to correct the problem. What do you guys think: low battery, rusty starter, corroded TPS, or all of them?

I have to confess, the last time I drove the truck was 6 months ago, so perhaps the starter rusted-up, the TPS got some internal corrosion, or the "healthy" 7.5 y.o. battery needs replacement. I don't usually drive the '04, since I have the bed loaded full of camping & car repair gear, yera-round. Instead, I have several old cars & trucks to drive (though my wife usually drives us in her low-mileage '14 Lexus ES350), and my usual choice is my current "project car", a 2001 BMW X5 3.0i. We also use a '98 GMC (hers), and an '09 HHR Panel (mine), as backups. And, at 74 (also, tomorrow), I don't maintain, nor drive my vehicles like I used to. All are on charger/maintainers, and get an oil change every 5k miles (or each year, whichever comes first).

I did notice that this old truck runs pretty darn good (139620 miles), with perfect fuel trims and MAF sensor readings...I wish my BMW could emulate that. since I've been fighting lean codes for three years on it (it is a "project car").

Edited September 25, 2024 by working on it

working on it · September 26, 2024

It passed the inspection, and now I have to determine whether to replace the battery, replace the starter, and/or renew some grounds, in order to make the truck start as good as it formerly did. $$$, even with me doing the work, or $$$$$ if I put it in a shop (not my thing, but I'm getting too decrepit to work under my vehicles for much longer).

working on it · September 28, 2024

Nice day outside, only 92F and a breeze, so I figured that I should start diagnosing the "slow-start" problem. I dug my old Century 200-amp wheeled charger from deep inside the garage (I haven't used it in probably four years), hooked it up to the truck, and voila, it started up as good and quickly as ever.

Still, i'm not yet sure if it's evidence of a bad/weak battery, or perhaps the starter has some internal rust (I've had two other parked vehicles at home, that needed a jump, or a hit with a hammer, before they would rid themselves of internal rust}, after sitting atop damp soil for more than six months, without a single start.

So, I'll start the engine about 5-6 times a day (both with and without a jump box or charger added), for a week, to see if there's still any signs of a slow start. By the end of the week, I'll most likely be sure that the starter itself is in OK shape, and that the 7.5 y.o. battery is the slow-start culprit. I always have a 1.25 to 2 amp charger/maintainer in use on all of my vehicles when parked (except for my wife's Lexus, because she can't be bothered with using one); that's why all my batteries usually last from 10-12 years...I haven't had to replace one this young since I started using charger/maintainers.

Edited September 28, 2024 by working on it