Issue:

One fine sunny day, turning into small streets after a 35km highway drive, my lovely car lost effective throttle control. Uneven/weak acceleration, pulsing idle, check engine light. Parked it on the first curb I saw: it started fine with no knocking/clanking/grinding, but did not idle or rev smoothly. I was pretty freaked out: it did not feel controllable!

Had to leave it on the curb for two days (Canada day!) before towing it to a Honda dealer. For $100 they could not reproduce the problem, even with a brief highway test drive.

• Error code indicated "p1362 tdc sensor no signal in circuit". A timing anomaly was noted via a sensor in the throttle assembly, and the ECU put the engine into a retarded mode.
• Associated flow diagram pointed to an "intermittent problem", since issue could not be reproduced.
• Checked loose connections at plug for TDC sensor (was covered in oil, cleaned) and pcm connections. Both good.
• Resistance at 2.335kOhm on TDC side, 2.350kOhm at other. Within spec, things look good...

Test driving it back, issue occurred again as I was turning left onto a highway. Accelerating from a full stop, throttle lost all power and got that "uneven" feeling. A few seconds of calm panic and mashing the e-lights - then while I was giving it gas the problem resolved itself. Off I went, with only the newly-lit check engine light to remind me anything happened.

History:

• Car's in good conditions, been mine for 9 months, no major accidents that I know of.
• Some oil and fluid seeps.
• Honda dealer that checked it over when I bought, said spark plugs needed replacing. Pretty sure that was make-work, ignored it.
• Same dealer indicated compression in one cylinder was at the minimum of the accepted range, but not below.
• Tachometer occasionally skips around a bit, especially at around 80km/h. My ears indicate this is a sensor issue.
• Automatic transmission kicks like a mule at low speeds, first 3 gears especially. Much of the time it's just a push, but when conditions are right (not sure what they are, but stop and go traffic encourages them) it goes *clunk* hard enough to make me wince. However, apparently hard-shifting is a normal property for this type of Honda... And the checkup at the dealer didn't find anything notable.
• I spend 36 out of 37km of my drive to work, on an wide and desolate Canadian highway in 5th gear.

Theory:

One guess I have, is that the *clunk* my transmission makes translates directly to the engine. Occasionally, the ECU notices this bump, assumes it's a timing issue, and freaks the hell out. Supporting evidence:

• The two times it's happened, was at low speeds+gears, where discontinuity is strongest.
• I spend so much time on the highway, the issue occurs rarely.
• It fits the "intermittent problem" diagnosis, which otherwise makes no sense since wiring looked good.

The only question is why did it happen twice in such a short timespan? In retrospect, it may have occurred before, but recovered so quickly (due to liberal application of gas pedal) that I wrote it off and thought nothing of it. I've had occasional "what the hell, I should be accelerating" moments, but they've been rare and brief enough to ignore as human errors.

How do I confirm if my theory's correct? Does it sound reasonable?

If not, what other possibilities are there?

If yes, how can I make the transmission kick less? Tuneups? Flushing transmission fluid? Driving technique?


I love this car, and want to fix this issue. Any help or comments would be greatly appreciated

 

It's a grounding issue and related to the distributor, I'm almost certain of that, but I don't know the exact problem, sorry.

 

Where is the sensor located on the V6 model? It's in the distributor on standards, but the dealership mentioned replacing the throttle body (~$1k for the part alone) to replace the sensor.

 

The TDC sensor is definitely not in the throttle body. Are you sure they weren't talking about the TPS?

 

The check code "P1362" definitely involves the TDC sensor having no signal. The parts guy doing the lookup said it was part of the throttle body and didn't come separately - but unless the V6 is different from the V4 he might've screwed up.

It being in the distributor makes more sense - they said they cleaned oil off the contacts, and there's an oil seep around there. I wonder if it just needs cleaning?

 

At least on the USA model, the TDC sensor for the 95 Accord V6 is mounted on the oil pump housing. Refer to this thread and the parts look-up link:

https://honda-tech.com/forums/honda-accord-1990-2002-2/tdc-sensor-questions-2840068/

http://www.hondaautomotiveparts.com/...AINER+%28V6%29

 

I've got it at a local Honda dealer now. Problem is fairly reproducible on low RPMs, though once you get to higher ones it doesn't seem to happen.

So far they've:

• adjusted the timing belt: noise reduced but problem not gone
• checked grounds and they're good
• checked resistance of sensor, looks good, but they're aware that it might still be bad

I'm having trouble trusting the representative I'm in contact with: he claimed the TDC sensor part is $4xx rather than $2xx, and is very lax on the details. Definitely gives the impression of being more interested in generating work than fixing the problem. Checking wire harness now - could try and test with a different ECU borrowed from a scrap yard for $50, but how often do those fail?

 

Oh dear. I just got a price quote of $391 for the CYP/TDC sensor assembly. Which is at least 50% higher than the previous quote I got, from their parts guy.

I don't think this shop is interested in fixing my car

 

The TDC/CYP sensor is located behind the front camshaft on your car. It's a combo sensor(Top Dead Center/ Cylinder Position sensor). If you look near the front valve cover there will be a 4 pin connector attached to the oil dip stick tube. The two wires that are for the TDC are colored Red and Green (two separate wires). You can ohm test the TDC, the specs are 1.5-3.0 ohms. Ohm testing is best done when the component is hot, so run the engine a while before you do it. I recommend using a DSO (digital storage oscilliscop) when testing these sensors, but if that's not possible a resistance test is a about all you can do. If you need any other help let me know.

 

Is that 1.5-3.0ohms or kohms? Shop reported "the tdc side has 2.335 k ohm in spec, then checked other side 2.350k ohms also in spec". Edit: looks like kohms, guess that's a typo.

 

Forgive me, you are correct. It's kohms.

 

The part number for the TDC sensor assembly on the 95 V6 Accord is 37500-P0G-A01, right?

Edit: it looks like the 96 part is listed here as not compatible with the 95 one?
Edit edit: come to think of it, the 37500-P0G-A01 appears to only be one sensor. Not two on a single line, like it should be according to the shop, and what I think is the right manual :\ So does this diagram.


Edit: nevermind! The shop checked the ECU, distributor rotor, and ignition coil with known good copies + tested fuel pressure. Those work fine. Apparently it's a crank position sensor issue - the code for it came up once, and there's records of similar symptoms occurring in hot US states. Which matches with my driving pattern of mostly-highway!

It's expensive in labor to replace, but it sounds like it should fix the issue once and for all