No power & Idle speed wanders up & down

[papacan]

I pulled the ECU feed cable to the TPS and tested it with the engine running. A is reading a solid 5.00 Volts to ground and 5.00 volts to pin B. Pin B is grounded (reads 13.3 Ohms to Bat. ground, 0.0 volts to ground).

Now for the realy interesting find of the day. While getting your answer I discovered that I had the connectors reversed, so pin A was connected to pin C, and Pin B to Pin B. No idea how I missed this before, or how long or often it has been crossed over like this. I did not realise this connector could be reversed and still connect.

So I drove it a few miles and the performance has changed considerably. At first the system was immediately idling much faster, like 1200 rpm. I turned off the ignition and restarted it after 10 seconds off time, and the idle slowed back down to 700 rpm. Now it is cycling between 800 and 450 rpm at idle and 700 to 450 in drive while idling. Not as bad as before. It also has more power and acceleration now, but still has some power, acceleration, occasional stumble on acceleration and idle cycling issues, just not nearly as bad as before.

I suspect from my findings today that many others here have inadvertently hooked the ECU to TPS sensor connector up backwards like I did, as they have reported similar, seemingly unsolvable problems idle problems. So check your ECU to TPS connections!!!!!

In my case the A-B-C is visable on one connector while PED is visable on the other connector when attached properly. In other words the A-B-C marking is top side on one connector and bottom side on the other connector when A-A, B-B, and C-C are connected correctly. This seems wrong to me that they are not on the same side, meaning I think they should be both display side up when connected correctly, but perhaps the new sensor I installed last year has the connector on backwards from the factory??????
:wow:

I may need to check the wires on both sides more closely to be sure, but since the performance is so noticably improved, I suspect I now have the connectors and wires attached properly on the ECU to TPS connection.

I've been working on a high idle problem,going from 600rpm cold start,when starts warming up creeps to 1200/1500rpm, I found the same thing with my tps conn. abc from ecu & ped from tps,so I turned the one from the tps over to match but it did not to accept norm'l,sould I force it together?to match?

 

[Ecomike]

"I've been working on a high idle problem,going from 600rpm cold start,when starts warming up creeps to 1200/1500rpm, I found the same thing with my tps conn. abc from ecu & ped from tps,so I turned the one from the tps over to match but it did not to accept norm'l,sould I force it together?to match?"

FORCE IT :gag: Definately not! If I understand you correctly, yours was attached correctly already. Are you saying the PED side of one connector was visable while the ABC side of the other connector was visable when originally connected? If yes, then it probably was connected correctly already. Look at both sides when connected that way and see if the A on one side connector does not in fact line up with the A on the other back side connector!

On mine, and I suspect most others the ABC side shows up on the front side of one connector while the ABC shows up on the back side of the other connector when they are properly attached!

That is what confused me into hooking it up backwards originally, thinking the ABC sides should both be visable on the same side. Also the interference clip on my wiring harness that normally keeps one from attaching them backwards was damaged enough and made it easy to fit the connectors together backwards with out forcing them.

But if both ABC sides are visable on the same side when connected(*) the A actually ends up connected to the C wire and the other C wire ends up connected to the other A wire (at least on the TPSs and wiring harnesses I have checked)

*Which requires a damaged clip on the wiring harness connector to hook it up backwards, if the clip is not damaged they will not attach to each other backwards, unless forced, thus damaging the clip, I think).

If I am wrong and yours was attached backwards like mine then you should not need to force it together , unless one if the pins is bent and no longer wants to re-engage. If that is the case it will not want to go back together in either direction. I had that probloem too, at one point and had to straighten the center B pin.

Keep in mind that when mine was attached backwards it caused the idle speed to cycle up and down contanstantly on about a 20 second frequency, not just up. For your idle problem, you might check the air temperature sensor in the intake manifold first and then the Idle Air Control (IAC) stepper motor in the throttle body next. Also an intake manifold or Vacuum leak that opens up and increases as the engine warms up could cause the idle to increase.

 

[thall]

Just a point...

Most, if not all, of the sensor connectors are "keyed" to where they only fit one way. As long as someone has not performed 'creative wiring' the connections should be correct...

unless you buy an incorrectly terminated O2 sensor like I did..... but it would not connect.... had two male plugs...

 

[papacan]

"I've been working on a high idle problem,going from 600rpm cold start,when starts warming up creeps to 1200/1500rpm, I found the same thing with my tps conn. abc from ecu & ped from tps,so I turned the one from the tps over to match but it did not to accept norm'l,sould I force it together?to match?"

FORCE IT :gag: Definately not! If I understand you correctly, yours was attached correctly already. Are you saying the PED side of one connector was visable while the ABC side of the other connector was visable when originally connected? If yes, then it probably was connected correctly already. Look at both sides when connected that way and see if the A on one side connector does not in fact line up with the A on the other back side connector!

On mine, and I suspect most others the ABC side shows up on the front side of one connector while the ABC shows up on the back side of the other connector when they are properly attached!

That is what confused me into hooking it up backwards originally, thinking the ABC sides should both be visable on the same side. Also the interference clip on my wiring harness that normally keeps one from attaching them backwards was damaged enough and made it easy to fit the connectors together backwards with out forcing them.

But if both ABC sides are visable on the same side when connected(*) the A actually ends up connected to the C wire and the other C wire ends up connected to the other A wire (at least on the TPSs and wiring harnesses I have checked)

*Which requires a damaged clip on the wiring harness connector to hook it up backwards, if the clip is not damaged they will not attach to each other backwards, unless forced, thus damaging the clip, I think).

If I am wrong and yours was attached backwards like mine then you should not need to force it together , unless one if the pins is bent and no longer wants to re-engage. If that is the case it will not want to go back together in either direction. I had that probloem too, at one point and had to straighten the center B pin.

Keep in mind that when mine was attached backwards it caused the idle speed to cycle up and down contanstantly on about a 20 second frequency, not just up. For your idle problem, you might check the air temperature sensor in the intake manifold first and then the Idle Air Control (IAC) stepper motor in the throttle body next. Also an intake manifold or Vacuum leak that opens up and increases as the engine warms up could cause the idle to increase.

My clip is damaged,so I'll go as is, the only thing I haven't checked is the IAT,would this effect the idle that much?

 

[Blaine B.]

Well once you get it figured out which way it goes in (with the damaged clip) put a ziptie on EACH end (the plug end, and on the end it plugs into)

Then tie both zipties together with a third ziptie......this will create a cheap way of making sure that it won't unplug! I've done it.....and it works.

 

[thall]

My clip is damaged,so I'll go as is, the only thing I haven't checked is the IAT,would this effect the idle that much?

Do you mean IAC?
If so, yes, it is ultimately what controls the idle speed.

 

[Ecomike]

unless you buy an incorrectly terminated O2 sensor like I did..... but it would not connect.... had two male plugs...

As my kids would say, "Now thats just gay" LOL:laugh2:.

Anyway, I hope my longwinded description below was detailed and clear enough about the TPS and O2 sensor connector problem I found on my jeep.

Once again, when connected properly (at least on mine, and it appears on most others), the ABC markings are and will be on opposite sides of the connection.

If you look closely, when they are on opposite sides, the A-A wires are actually connected to each other, same for B-B and the C-C connections.

Yes that seems wierd, which is how and why I made the earlier mistake in the dark one night of connecteing them backwards when I removed and cleaned the connections). As stated by others, it is generally not possible to connect these fittings backwards. But if your wiring harness connectors are getting old and brittle like mine have, then the clip parts that allow the connectors to attach only one way can get damaged. When that happens it becomes possible for the connectors on the O2 sensor and TPS sensor to be connector backwards at least on the older Renix systems.

 

[thall]

yeah.... but it was not my fault!!! blame some packaging Xpert in god-knows-where country of origin!!


.

 

[papacan]

Do you mean IAC?
If so, yes, it is ultimately what controls the idle speed.

It goes by many names I guess, I guess I would call it a manifold air temp sender or sensor,not the IAC,I check it & cleaned it.