As I note in my other thread, just did an Opti swap, and while it went well, I did end up w/ 3 DTCs: 22, 23 & 48. The 23 & 48 were both MAF-related and easy to resolve. However, the 22 is proving to be a real PITA.

WHAT I'VE DONE:
I've tried 3 diff TPSs--2 ACDelcos & an adjustable Standard Ignition. While the ACDs are consistent, I get diff readings from the SI. Troubleshooting I did:

1. With connector off, KOEO, tested reference voltage (grey wire) and get a solid 4.99vdc.
2. Checked ground (black) wire and get a good tone every time. Ground is good.
3. Back-probed. With the connector back on, tested the signal (dk blue) & ground wires. At KOEO, the ACDs both show .31vdc; the SI shows .65vdc. This is consistent w/ what I show in the scans I've run, and is within FSM tolerance.
4. Actuated the throttle manually, and for all 3 TPSs, the result is the same: voltage drops, rather than rises. This is also consistent w/ what I see in the scans; while a DTC 22 pops up @ diff stages between the ACDs & SI, they all throw the code. With the ACDs, it comes almost immediately; as soon as I start it, voltage drops to .29 and a code pops up (even tho it isn't supposed to until ~.23). With the SI, it doesn't come until I hit ~1800 RPM. For all 3, voltage normalizes after I let up on the throttle, but since this is a saved code...

I read a rather long thread (6 pages) in here on DTC 22 (from 2014), and in the end, the OP noted he tried 3 diff TPSs before the problem was resolved. I'm already thru 3, and it seems odd that I would get 3 bad ones in a row--altho I suppose it's possible.

So my question is: am I sitting on a string of bad TPSs? Or is there something I'm missing? I'd really like to drive this thing, and it looks like a ~$50 part is the only thing holding me back.

 

Fred (Injuneer) is more likely to have reliable advice, but as a shot in the dark: try a different throttle body?

My thinking is that if multiple sensors are all giving weird signals, then maybe something is wrong with the thing being sensed.

 

Sounds to me like the TPS connector has intermittent connection. Start the engine, let it idle, have someone watch the trouble light in the gauges while you wiggle the TPS cable/connector. Does it fail then?

 

I wondered 'bout that. I had removed the TB to lift it outta the way when I put the WP back in; it's lots easier to seat the WP (and not disturb the gaskets) that way. I had a Felpro TB gasket, but noticed the existing gasket was much thicker. Some of it was stuck on the TB, some on the plenum, and it wasn't easy getting it off. It almost seemed like it was some sort of plastic rather than gasket mat'l. Otherwise, the TB was very clean; no blow-by, no deposits, etc. I hadda get the existing off to use the Felpro, but I wondered if that wasn't a gasket, but part of the TB. Still, it went back together fine. I also checked the linkage & cables and everything moves smoothly.

The 2 MAF codes were easy to resolve. W/ the CAI I have (K&N), it's a challenge to get everything seated just right, and that was the issue here. Once I took it all apart and reseated everything, those codes vanished. Doesn't seem like these were electrical-related (altho they are sensor codes), but rather some so-so reinstallation on my part. In contrast, the TPS issue is clearly affected by voltage.

 

When I ran early scans, I did get intermittent SES, which roughly mirrored what I outlined w/ the various TPSs. With the ACDs, while they throw the code as soon as I start it, the SES flickers, then goes out when idle drops to ~800 RPM. The SI is more sensitive to throttle input (~1800 RPM), is less likely to show the SES, and it goes out quickly when I let up.

One thing I noticed, when I ran a scan before replacing the Opti, the battery ran low trying to start it--down as far as ~6vdc. This was within ~10-15 seconds. So I figured from then on, I'd leave it on a trickle charger when I wasn't working on it. But everytime I do that and hit the button for the FLO charge, it tells me voltage is way down--to ~25% of full charge. It recharges and kicks into FLO w/i a few minutes--and I've had no problems starting it--but I wonder if that is affecting the TPS. I did test the ALT, but it shows as good. On subsequent scans--after being on the charger--voltage stays btwn 12.8 - 13.4. I wonder if I have a funky charger or a funky battery.

Imma take the FLO charger, put it on my Jeep & see if I get the same result; if not, it suggests I'm losing voltage from the battery. If I do...hmm. I'll leave it off the Z, start it (I hope) and then try wiggling the cable to see what happens. Something is causing a voltage irregularity that is causing the TPS to act directly opposite of what it should, but I can't pinpoint what it is.

 

OK, put the charger on the Jeep & got same result, so there's no issue w/ batt voltage, which is supported by the recent scans. That's just what my charging unit does.

Also tried wiggling the cable when running, but got no SES or DTC. This appears to be entirely dependent on throttle movement.

Took another scan--w/ the ACD TPS--and got diff results from other ACD scans; it didn't throw the DTC immediately, like on prev. scans. This time, it wasn't until more than a minute of scan time. From the data...

Briefly, @ 30.79 (row 254), it flashed a DTC 11 (SES). However, the SES didn't actually come on--at least not @ that point. Likewise, @ 37.72 (row 309), it briefly flashed a DTC 16 (low res signal). Since these were so brief & only appear in a single row each, not sure what (if any) relevance/emphasis it would have.

It wasn't until after I had gradually increased throttle that 22 came up & the SES lit. This was @ 85.64 (row 696), w/ engine RPM @ 1227. The SES remained thru the rest of the scan, even after I backed off. Even then, RPMs still were a bit higher than normal. It came down when I ran thru the gears briefly (shifted rough, but thats expected w/ a 22), but after that, RPMs stayed over 1100 thru the end of the run. TPS voltage started @ 31, dropped to 29 @ start, and hovered btwn 24-29 until 83.50 (row 678), when it dropped to 22 (ironically). The DTC & SES came ~2secs (18 rows) later.

Bottom line: dunno. Something is causing TPS voltage to drop when throttle is applied, but ONLY when throttle is applied. I had no idea why it didn't like that MSD coil I put in, but I replaced it w/ a stock coil and the DTC disappeared. I don't have a stock TPS, but I'd love to see what would happen if I did. Nor do I think this is PCM related, given that everything else seems normal. I still wonder if I just got a bad string of TPSs, but it seems very odd to get 3 in a row. Maybe I should see what other brands are available locally & given 'em a try.

 

Just bought 5 diff TPSs, will have 'em tomorrow & give 'em a try. Maybe 1 of 'em will work out.

I wonder if this is PCM-related; not a bad PCM exactly, but since I've made some changes... Individually, nothing I've done would require a tune. The injectors are Bosch III 24lb., the Opti wouldn't require it, exhaust, CAI, fuel pump (w/ only slightly higher capacity), ICM (didn't toss the orig), etc. I had the issue w/ the MSD coil, but returned it to stock and the problem vanished. Aside from that, none of these things triggered a problem--only the TPS. But I wonder if collectively they affect the tune in some way. I just don't know enough 'bout PCM tuning to tell. I asked Keith @ PCMforLess about it, but he said they'd need to have the car. Hmmm...

Let's see what happens w/ the various TPSs. All the diags point to it, but it just seems crazy that I'm 0-for-3 so far.

 

Shoulda trusted the diags more--I did get 3 bad ones in a row. Dunno if it's ACDelco & Standard Ignition or O'Reilly, but it's a sad state of affairs, and really drives you crazy second-guessing yourself. The 1st three from Autozone all worked fine (didn't try the last 2): Duralast, Dorman & Delphi (hmm--alliteration). The Duralast seemed a bit more responsive on the multimeter (they included a connector), so I'm running that, will keep a spare & return the rest. Guess I shoulda known; if you're back-probing @ the TPS and the signal ain't there, the PCM doesn't really come into play.

Still, I'm not 100% convinced I'm outta the woods yet. I ran a scan and it kicked up 5 DTCs (63, 13, 25, 24 & 21--imagine that), but it was like above: all were for a single row, none of them set. Those are all circuit-related, so I'll need to watch that. It's one thing to scan it in the garage, another out on the road. I'll take it out, get a road scan & see what happens.

Lesson learned: you just can't trust the parts you get these days.