Ignition related issue, no tach

[TajMan]

Trying to diagnose on my 94 TT, no tach and I have a miss like a coil is down or at least 1 cylinder down. Rich dumping the fuel, its ignition related.

I've had the upper plenum off many many times doing plugs wires compression checks all that, and have flow-tested my injectors, I have two sets of coil packs and 2 PTU's (from this and '93 VR4).
Both Power Transistor Units test fine per Stelath316 and using a battery/meter to test.
The '93 VR-4 coils: one of the coils ohms out like its going bad I'm not using those.
I'm running the factory 94 Coils that all ohm out good.

After swapping the PTU's back and forth and getting nowhere and testing them again to verify ok, I've been trying to check wire continuity between the ECU plug and the PTU connector.

'94 Fed spec TT, https://www.3swiki.org/ECU:_94-95_TT...l_Spec_Pinouts
Pins 10, 11, 23 on the 26-pin C52 connector are the 3 PTU wires

On the PTU connector side. the 3-pin connector 11,12,13
http://stealth316.com/2-pwrtransunit.htm
if I try to ohm out through a long test extension wire, doesn't matter which I try 11 12 or 13 I get a reading of like 30.x on all 3 at the same time instead of the 0.0 or 0.x I'm looking for from one of the 3 singular I'm trying to check.
hard to verify I'm getting solid connection through test wires and small-nail I used to probe a female connector inside the car at the ECU plug..

I DID have a MAF Translator PRO previously installed which I reverted back to stock at the ECU plug. All wires were soldered/heat-shrinked and I'm 99% sure my issue isn't a wiring issue there.
Any tips recommended I'm banging my head.

-Taj

[OhioSpyderman]

Crank sensor?
ECU?

Just tossing out possible reasons for not sparking on 1 coil (2 cylinders....wasted spark)....

Bob.

[TajMan]

Crank sensor?
ECU?

Just tossing out possible reasons for not sparking on 1 coil (2 cylinders....wasted spark)....

Bob.

Yes thank you.
confirmed coil for cylinders 1 & 4 isn't working.

Suspect ECU now.

Can I get in touch with someone who does ECU testing and repair, Chromed/Jester people?

[OhioSpyderman]

https://www.ebay.com/itm/32412978896...Bk9SR66t_bbGYQ

From what I've read, this business is REAL and can fix FUXORED ECU's

Never used them, but again, they have some good 3SI reviews....

Bob.

[TajMan]

https://www.ebay.com/itm/32412978896...Bk9SR66t_bbGYQ

From what I've read, this business is REAL and can fix FUXORED ECU's

Never used them, but again, they have some good 3SI reviews....

Bob.

Well that's good if they've had good 3/S reviews.
I'd seen that exact auction on ebay already, but seen their feedback and said NOPE, haha

I bought a new used ECU so we'll see how that works for me, but yes I still want to try and get the spare fixed.

[j2k4]

I'll bet Blackstealth could tell you...

[TajMan]

I just swapped the ECU with a spare,
and SAME ISSUE, ugh.

Now then, back to where I was trying to diagnose first. I was trying to trace the 3 PTU wires from ECU pins #10 #11 and #23 of the largest connector.
Can anyone tell me where the other 3 ends trace to, the PTU plug? For coil A B and C. I was unsuccessful in tracing continuity between those wires before. (got partial resistance from 3 wires at PTU plug, but no verified dedicated connection)

[OhioSpyderman]

https://i.imgur.com/t6DIiKi.jpg

Hope that helps...

Bob.

[Nash94GTOTT]

Have you figured out why your tach doesn’t work? I’m having a similar issue. My tach can barely make it to 2krpm. I replaced battery, plugs, wires and ptu. Still not working properly.

[OhioSpyderman]

A sluggish tach is usually signs of failed capacitors inside the tach mechanism (just like the crappy ECU capacitors).
If you're handy with soldering tools it's a fairly simple job.
Plenty of stories about failed tach's on the "other" 3S site (cough, 3SI.org, cough).

Bob.