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Super Mechanic
Super Mechanic, Master technician
Category: Chevy
Satisfied Customers: 17217
Experience:  29 yrs. exp., ASE master, cert. in G.M. electrical, a/c, susspension, brakes, electronic steering
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1991 Chevy: Cylinder..) with Throttle Body Injection..Cruise Control

Customer Question

I Have a 1991 Chevy S-10; it has a 2.5 Liter (Inline 4-Cylinder) with Throttle Body Injection, Manual 5-Speed transmition, NO A/C, Cruise Control, ABS....ect. Basic S-10. I installed a new engine into this vehicle, but due to the fact there is no V.E.C.I. lable anywhere in the engine compartment; I have no idea (except for a Haynes manual; not helpful here) on WHERE? the "brown wire with black or white stripe" is located. (I assume this wire is like the vacuum advance on a distributer.) Also I would appreciate what I am supposed to set the timing at; and does the engine r.p.m.'s matter? I am comfortabe working with carberators and older points type ignitions. I have a dwell/tach meter, and also a "basic" timing light for the crank/harmonic balancer. Also I had a freind who told me the the wire I was to disconnect was UNDER the glove box. I found a brown wire with a black stripe, but it went directly to the E.C.U., and I was unable to find a disconnect. Any help here would be appreciated... I work on a farm in Reeder, ND and the nearest Chevy dealer is an hour away in Dickonson, ND
Submitted: 5 years ago.
Category: Chevy
Expert:  Super Mechanic replied 5 years ago.

Hello and welcome to Just, Super mechanic here. Please DON’T hit accept until you are completely satisfied with the answer. If you need any more on it just let me know. About your vehicle.

1991 Chevy Truck S10/T10 P/U 2WD L4-151 2.5L

The timing connectors that you had to unplug was used in the V6 engines. The 4 cylinder engine's you just have to ground the diagnostic connector.



Set timing under the following conditions:

  • Normal operating temperature.
  • Air cleaner installed.
  • A/C "OFF".
  • Transmission in neutral.
  • Put electronic spark timing (EST) in by pass mode. Connect a jumper lead between terminals A and B of the ALDL connector under the dash.
  • Connect timing light and adjust as necessary by loosening hold down bolt and rotating distributor.
  • Tighten hold down and recheck the timing.
  • With ignition "OFF", clear ECM trouble code by disconnecting ECM power source.
  • With engine at operating temperature, drive vehicle at part throttle with moderate acceleration and decelerate to idle condition. This will "teach" the ECM/VCM and return the engine to normal performance.

Engine 2.5L (151 cid) Base Timing 8~ BTDC (Manual Trans).
Engine 2.5L (151 cid) Base Timing 8~ BTDC (Auto Trans).

1991 Chevy Truck S10/T10 P/U 2WD V6 2.8L




Customer: replied 5 years ago.

Currently, it is 2100 Hrs MTN time here. Way to late for me to check your info you've provided. I will attempt this procedure upon returning to work, since at that point my enginge will be warmed up. I honestly believe you have got the answer I am looking for. I will respond tomorrow with my results if this is acceptalbe to you. My home num ber is XXX-XXX-XXXX, my work number is XXXXX If this works, you have your money; by the way, how do i get back to you or this website to "accept" your answer?

Expert:  Super Mechanic replied 5 years ago.
No problem it's late here too, (eastern time) and we can't even see phone numbers on this end, (lol) but, you can log back on here with your user name and password, as far as I know, whenever you are ready, thanks (P.S., even after you accept you can follow up at anytime)
Customer: replied 5 years ago.
This was a one shot deal, I believe, I have no user name or password; as a matter of fact this is the first time I've been on the internet in over 10 years. So since I am not a subscriber. How can I get back here unless I stay on line, or keep my computer on. Niether of which I prefer to do....
Expert:  Super Mechanic replied 5 years ago.
I am pretty sure they will send you an email. Other than that I couldn't say for sure but I do have customers that get back after several months though.