S-10 2.8 wiring

[Rand Man]

Hi, I recently picked up an '86 Chevy S-10 pick-up. It has a 2.8 V6 and is a 4x4 extended cab. I'm new to this forum. I tried to search for S-10 and 2.8, but found nothing in this section. I'm not sure where to ask these questions.

The truck sat for two or three years in this guy's back yard (the woods). Some varmint made a nest under the hood. There are a few wires chewed off.

The engine is a little hard to start. When it does start, it revs-up a lot, then settles down to a decent idle. What can I do to fix? I want get all the basics straightened out, then go for performance.

[SappySE107]

I moved it to wiring and changed the title to something relevant since this is not performance oriented. Sorry I can't help but I don't have a wiring diagram for the 2.8 S-10.

[RacerX11]

Where are the wires that are chewed off? Does it have a carb or TBI injection? Is the check engine light on?

[Rand Man]

There's one spot chewed off right behind the water neck, on top of the intake manifold. It's a TBI model. I'm thinkning it's the water temp sensor. The check engine light comes on about the time the RPM settles down.

[bszopi]

Hey Randy, glad to see you made it over here. First thing would be to pull the codes and go from there. In order to pull the codes, do the following:

1. get a paperclip or piece of jumper wire.
2. take your keys and put them on the seat so they are not by the ignition switch (just for precautionary reasons).
3. insert the paperclip/jumper wire into the two slots to connect them.
4. insert your key into ignition switch.
5. turn ignition switch until only the warning lights on the dash light up and look at your service engine soon/check engine light which should begin flashing after three seconds. DO NOT START THE ENGINE!!!
6. count the number of flashes to determine the engine code. The first code will ALWAYS be a Code 12 (demonstrated by a flash, a one second pause and then two more flashes), and each code is repeated three times before advancing to the next code.
7. just watch the light as the codes display the first time to be sure that you understand what the number of the codes are. The codes will continue to loop back around to 12 and repeat. After the codes begin to repeat, write them down.
8. once you have written the codes down, turn off the ignition switch and put your keys in your pocket.
9. remove the paperclip/jumper wire from the ALDL.
10. call Autozone to get the code meanings and use these as a starting point for solving the problem.
11. disconnecting the negative battery cable for 30 seconds is used to clear the codes, but should only be done after checking/replacing the parts affiliated with the trouble codes.



Post whatever codes you get here, and we can go from there.

[geoffinbc]

The front yellow and black wires are for the temp sender. It makes sense that it causes the idle to be off since it tells the ECM the temperature of the engine and in turn the amount of fuel to add.

[Rand Man]

My son got the codes today. I'm not sure exactly how to post them. Does this make sense?

12, 15, 3, 3, 45, 12 . . .

I'll try n contact Autozone tomorrow. Thanks for the help.

[bszopi]

I think this is the correct table to look at: http://www.troublecodes.net/GM/86-87_289_mfi.shtml

Codes would be:

15: Coolant temperature sensor signal indicates a temperature colder than -47° F for 3 seconds.

33: MAF sensor indicated air flow was more than 20 gm/sec for 2 seconds.

45: Oxygen sensor voltage was over 0.7 volts for 30 seconds in a closed loop when throttle angle was between 3% and 45% and engine had been running for at least 1 minute.

Looks like Geoff was on the button with the coolant temp sensor. So that might be a place to start. Then replace the O2 sensor as well. Not sure about the MAF issue, unless it was set due to the revving up of the engine.

[RacerX11]

This is a TBI engine, not MPFI, so I think this would be the corrct code list: http://www.troublecodes.net/GM/87_28RTBI.shtml

This would make the 33 code MAP, not MAF. Like Brad said, start with the coolant temp sensor since you know at least those wires are messed up.

[Rand Man]

Thanks, You guys aere great. I've been so busy at work, I havn't had a chance to pick up a new sensor. Does anybody know a good place to find a wiring diagram for this truck?

[RacerX11]

If the wiring is chewed through, you shouldn't need a new sensor...just repair the harness.

[geoffinbc]

Thanks, You guys aere great. I've been so busy at work, I havn't had a chance to pick up a new sensor. Does anybody know a good place to find a wiring diagram for this truck?

I have the engine control wiring online.

http://members.shaw.ca/betterthanyoutoo/ecs1.jpg

http://members.shaw.ca/betterthanyoutoo/ecs2.jpg

http://members.shaw.ca/betterthanyoutoo/ecs3.jpg

http://members.shaw.ca/betterthanyoutoo/ecs4.jpg

http://members.shaw.ca/betterthanyoutoo/ecs5.jpg

[sotlm2]

i have a 92 s10 with 2.8 that my father and i have owned since new. it has 184,000 trouble free miles. With that being said, my truck (since new) starts with a high idle and then settles down after a minute or so. Believe it or not, it does have the original o2 sensor but i have no check engine light. I plan on changing it this weekend. But the point is, i think its normal for these trucks with a 2.8 to idle high at cold. Now my 4.3 (same year) never idle'd at startup.

[geoffinbc]

Yes they absoutly should idle high wen cold. Depending on temperature it should be 1200 to 1600 rpm

[Rand Man]

Well it had been running OK for a while now. IT's started running really rough now. My son says it will hardly go over fourty miles per hour. You have to find the "sweet spot" on the throttle of it will sputter and backfire (under the hood). The codes now read: 33, 44, 45. Any Ideas?