Rough Idle/Hesitation/Backfire

[Gary Yarbrough]

Well....I changed the coils today and the problem is still there. On the upside, I now have a very strong spark when I pull the plug wires. So, it's plugs tomorrow (if I get a chance). I have three questions:
What's the proper torque for the plugs when i put them in?
How do I get out the rear plug on the passengers side?
Any other suggestions for what I should be looking for?

Thanks for any help I can get!

[XfireZ51]

Originally Posted by XfireZ51

DVM the TPS sensor. Also, while the car is idling jiggle each of the three wires on the TPS.

? Anything?

[Gary Yarbrough]

Maybe the TPS is my problem. I saw three wires: blue, white and black.
Between the back and the other two, I get ~4.5 and 4.0 volts. Does that sound possible and what's next?

[Kb7tif]

Originally Posted by Gary Yarbrough

Well....I changed the coils today and the problem is still there. On the upside, I now have a very strong spark when I pull the plug wires. So, it's plugs tomorrow (if I get a chance). I have three questions:
What's the proper torque for the plugs when i put them in?
How do I get out the rear plug on the passengers side?
Any other suggestions for what I should be looking for?

Thanks for any help I can get!

Did you use d545 coils?

[Gary Yarbrough]

I used Accel coils.

[ZR1Vette]

Rear plug... bit of a challenge but basically you need a plug socket, short (1 1/2") extension, universal and then a longer (4") extension

Have you checked your ALDL/DIC for any fault codes?

[tomtom72]

Just thought you might look this over about #8 plug r&r...

http://www.zr1netregistry.com/ZR1_techtips.htm

This is the ticket. 20 N-m ( 15 lb-ft ) on the 90 plugs w/the flat seats & flat washer.


Tom

On the TPS, Black is sensor ground, Dark Blue is the signal to the ECM, and Grey is 5v reference signal from the ECM. ckt #'s 452, 417 & 416 respectively. Therefore you should read the TPS signal from the TPS to the ECM at the Dark Blue wire. A back probe on the Dark Blue (417) should yield a reading between .46v & .62v. If I understand the book correctly.

[XfireZ51]

Gary,

With key ON, the TPS signal (between black wire and blue)
should be around .54v. Once you have it set up, read the TPS signal voltage as you open and close throttle with motor off but key ON. See if the voltage change is smooth or changes in a "choppy" manner. Does the reading change abruptly? Also, make certain the TPS switch assembly is securely attached and not loose. Move switch wires around and make certain voltage readings aren't changing.

[Gary Yarbrough]

I checked the TPS voltage. I get 0.37v. With smooth pushing of the accelerator, the voltages fairly smoothly (maybe 0.5 or so v increments). Flooring it, it goes from 0.37v directly to ~2.5-3.5v. Time for a new TPS?

[tomtom72]

Gary, I have a 90 and I know for sure that my TPS is adjustable...to what degree I don't know, but the screws that hold it in place are in slotted holes, therefore I conclude it's adjustable.

You may want to look closely at those screws as you maybe able to make an adjustment. If you say that the needle on the VOM moves thru it's sweep at a smooth progression then maybe an adjustment is in order.

Just a fwiw, try it, in the end you can always go spend the money if the adjustment don't work.


Tom