Txdragon

Hello all, I'm new to Honda but not cars. I have a 95 DX with mostly stock D15B7. I/H/E and short shifter are the only mods. I finally pulled the codes from my CEL and I got 3 and 7. Here's the issue... I've tested voltage at the tps pigtail and got .15v. Tested at the connector by the passenger shock tower and it is 3.25v. I stripped a bit of sheathing off the wire on the male end reconnected and checked volts, it's .15v. This rules out a short along the harness to the pigtail. I seem to have a couple issues here since I'm below 5v on the power wire at 3.25, but also losing 3.1v across the connector somehow..

eghatch9295

iTrader: (1)

do you have them switched around?

JarvisW

You should be backprobing. Stripping is asking for problems later.

but yeah, it sounds like its backwards. did someone else install the engine, or hack the harness?

Txdragon

Harness looks intact, at least as much as I can expose without removing the intake manifold. Impossible to cross as the tps pigtail will not reach the map sensor. I plugged the map pigtail into the tps in case it may have been spliced incorrectly, and no change to how the car drives. Odd it would even start like this. Lol

Guess this would have more than just me stumped. Hoping to find somebody with some knowledge I myself do not possess nor have found by way of Google. I've searched and found great testing info and diagrams to check wiring but aside from usual corrosion and anything that visually stands out and such, which is nonexistent, I can't figure out wtf.

Former User

Do both codes return after resetting the ECU?

Post pictures of the TPS and MAP sensor connectors, including the three wires for each sensor.

Does the engine start and run? Any performance problems?

Txdragon

Both codes return after ECU reset.
Car starts and runs, hesitates a little under load; uphill etc. You can feel very choppy pull when you get on it on the highway but otherwise drives OK. It is DUMPING fuel/running rich. I'll get some pics up soon. What I find really odd is that the car will operate exactly the same without tps or map sensor even plugged in.. Good limp mode I wonder?

tony_2018

Whats the voltage of the middle wire on the TPS?

Txdragon

I've tested voltage at the tps pigtail and got .15v. Tested at the connector by the passenger shock tower and it is 3.25v. I stripped a bit of sheathing off the wire on the male end reconnected and checked volts, it's .15v. This rules out a short along the harness to the pigtail. I seem to have a couple issues here since I'm below 5v on the power wire at 3.25, but also losing 3.1v across the connector somehow

tony_2018

I'm sure thats incorrect, check the 1st wire and 3rd wire. 1 is ground and the other should show 5v. Right Ron?

Former User

Depends on whether OP is doing voltage tests with connector unplugged or plugged in.

Three TPS wires are input voltage, output voltage, and ground.

It's critical that you post the pics before doing anymore tests.

Txdragon

The red is feedback to PCM, green is ground, yellow is supposed to have 5v KOEO. Red is supposed to read .5v +/- at closed throttle, 4.5-5v+/- wot. Green shows good continuity, red gives no change at all through any range of throttle position. Yellow reads .15.

tony_2018

Than you found your problem, not figure out if its out of spec or the tps is fucked.

Txdragon

I'm wondering about why am I at 3.25v at the shock tower female connection and .15 at the male connection all the way to the tps pigtail

Former User

None of the wires you mention are solid colors without a stripe. The colors of old wires could lead to confusion between the MAP and TPS. Post the requested pictures or accurate wire colors.

Also explain how you are making the voltage measurements.

Txdragon

I know the colors! I didn't figure typing in "yellow with white stripe wire" blah blah blah. I'm testing with a multimeter probe according to the testing write up I found on this very site, and information exerpt from helms.
I can't resize the pics on my phone.
I know those will help make a bit more sense on what I mean by shock tower plugs.

Former User

Refusal to provide requested information will get your thread locked. Please read the forum Rules sticky.

Txdragon

I'll get them posted as soon as the sun comes up this morning! I need to retake them. My phone was acting retarded transferring them and things got worse from there. I was called in to work yesterday afternoon, blah blah.
I'm not being difficult! Anywho, I thank everyone even attempting to help out on this!




Tps pigtail wires





Passenger shock tower connector block





Shock tower block female connector. (Power point for powered stuff)





Shock tower block male connector. (Wires to the tps and maf traced back to here.)

Txdragon

There is solid power going to both tps and map sensors unless either is plugged in while I am checking the other. Example: both unplugged, I test power wire on either plug and it reads 3.46v and drops slowly. I plug map, read power wire to tps pigtail, it reads .15 and stays steady. I plug in tps and read map power at pigtail and it reads .15 and stays steady.
Power reads 3.46v at the female block on shock tower so harness is good up to there.

tony_2018

Suppose to be 5v, thats not solid to me.

Txdragon

I know it's below 5v and that itself is an issue I have no concerns with. My concern is the consistency in what little voltage it IS getting and why it is acting this way. Even if it were 5v, I potentially face the same issue with my sensors plugged in as they should be.
If I replace my PCM because I'm not at 5v, I would like to know if the problem I describe here will still exist or not. UNLESS the consistency problem exists only because the PCM is fragged?

Former User

Lower than 5V is an issue as is the voltage drop when plugged in. Sounds like a bad ECU.

What are you using as ground in the voltage tests?

Txdragon

Battery ground for voltage tests, ground to plug/red to + battery for ground tests.
I understand that because I'm below 5v the pcu is buggered, but would that cause the issue I'm having between the 2 plugs while one is plugged in?

Former User

What are voltage readings when you instead use the MAP and TPS ground wires as ground?

Both results are consistent with a bad ECU, assuming that the reference voltage wires pass an Ohm test and the sensors themselves do not have a short to ground.

Txdragon

Didn't check that yet with my new discovered info on the crossover issue.. Gimme 5 min and I'll check.

Former User

Incomplete thought?