i have a 94 chevy s10 blazer. cant seem to get the timing right its either too far advanced or retarted. but it was driving fine untill today, it started backfiring and bogging under accleration. it has the poorest idle when it wants to idle. any help would be greatly appericated.. thank you

 

I have only two suggestions:

1. Make sure you're following the proper procedure to put the computer in bypass mode to set the timing. I've never done it on a Blazer but I know there's a particular wire you need to ground.

2. Check your EGR for carbon blockages.

 

Do your '94 S10 Blazer have to be time by the computer. Because I had to take my '95 S10 Blazer to the shop and they had to time it from the computer and not with the time gun then it ran alot better. Just something you might want to ask.

 

i followed all the preceedures to the T. and no obd1 you manually have to time. obd2 is 95& up and the computer controls the time.

 

The ECU still does control spark timing in your truck. In order to properly time the older ignition systems, you must first disconnect the brown (or brown with a tracer line on it) wire inside the truck, to the passenger side of the transmission tunnel, slightly below the top of the carpet at the firewall. If you didn't do this, you didn't properly set the base timing.

 

At least I learn something new now.

 

yes, i did disconnect the connector. i pulled codes for a map sensor and a tps sensor and replaced them. now i have codes for a knock sensor and ignition circut malfunction. now it idles fine except for it surging here and there but as soon as you hit the gas pedal it feels like it has a miss and once you get it to 3000 rpms the check engine light comes on and it spits and sputters and then the revs up to 4000 and drops down to 3000 again like it shut off and it will keep doing it untill you stop.

i am starting to think fuel pump or spider injectors.

 

Do you hear any rattling at all when the engine is running? I'm thinking you might be chasing symptoms and not necessarily the problem. You may have a clogged catalytic converter. To narrow it down, try disconnecting & removing the O2 sensor ahead of the catalytic converter. If the truck runs as it should (minus the check engine light for the missing O2 sensor), then the converter is clogged and needs to be replaced.

If you don't have a converter, then you may want to test the compression & cylinder leak-down to see if you may have another mechanical problem that may be triggering the knock sensors, decreasing performance.

 

no cat on it. theres always been a very faint taping, or knocking.