okay so i just got done doing a bunch of work on my truck,
I did:
head gaskets
intake gaskets
new injectors (bosch gen 3)
headers
valve cover gaskets
header gaskets
plugs wires cap rotor and coil
new motor mounts
distributor
ignition module
a guy on FSB posted a Write up on how to set your timing and i followed it to a t, the engine shakes pretty good goin down the road, like theres one cylinder not firing at all, at first i had no power so i gave the dizzy a lil twist toward the passenger side and it picked up quite a bit and it seemed to smooth out though not entirley im not sure if i need to time it better, IMHO it sounds like its got a dead cylinder (damn universal plug wire kits) the first thing i plan on doing tomorrow is pulling all the wires and check for continuity if they all check out im not sure what to do, dizzy's new modules new i cant hear a miss and im sure i would with a straight pipe, what i did was i bumped the motor over with screw drivers till i felt that gush of air i then set the timing to 10 degrees BTDC the marked it with a yelloe paint pen, the other ten (ATDC) i marked with a red paint pen, when i pulled the head off number one cylinder was flush with the deck so i know that im on the compression stroke, the when i dropped in the new distributor, i centered the rotor with the number one terminal when i started it i could see the ten mark was holding steadfast with the upper edge of the timing indicator ,when i bumped the dizzy to the p-side it went up to the 14-16 mark on the dizzy the thing this guy left out was how much i need to advance or retard the timing, i dont know where im supposed to be at BTDC 20 degrees 30 degrees? i havent a clue ill refer to my book but i doubt its be of any assistance can you guys help? whats the total timing suppose to be at?

 

help me guys i dont wanna blow the motor

 

When you set the base mechanical timing to 10 degrees BTDC, did you do it with the SPOUT plug unplugged? If you did not pull the SPOUT plug, then the ECM will be trying to adjust timing, while you are trying to set it.

Don't know if that's your issue, or not.

Separately, with the 5.0L, the sparkplug wires to cylinders 7 and 8 must not run parallel and next to each other, as the 302 firing order is prone to cross-fire between those two plugs.

 

Spot-on info there, pretty much nothing to add, but to ease things further:

- Warm the engine up, then kill it.
- Disconnect the SPOUT and plug your timing light to the #1 sparkplug.
- Loose the Distributor bolt, start the engine, and set the base timing at the stock 10° BTDC.
- From there, start working small timing bumps (advance the timing) by turning the Distributor clock-wise, until you hear any pinging (usually around 14°-16°), then back it up a little and tighten the distributor bolt back.
- Get in the cabin and start pushing the pedal slowly through the rev range, try hearing any pinging, if there is any, back the timing further and repeat this step.
- If there aren't any other issues you're pretty much done, kill the engine and plug the SPOUT back in.

Things you might want to look for:

- Sparkplug gapping for advanced timing should be around .055.
- Avoid the crossfiring issues mentioned by Torky.
- See that all the cable boots are grabbing the plugs firmly.
- Look for burned sparkplug cables, making any contact with the manifolds will cause this, look for broken cables for any other cause.

These are the basics, you could be having problems related to the PIP or even ECM, but I would check all the above first, also, pull codes to see if anything else is out of order.

 

I , like Encho , like to start with base timing . Then adjust by " ear " to get the best out of your engine . Sometimes base is a bit off for your engine .

 

just found that its not running on cylinders 7 or 8 the injectors for those cylinders are really quiet until i put a lil pressure on the ear pieces on my stethoscope then i can just barley hear em im going to be checking for spark in a few minutes

 

so ive checked all the cylinders for spark and they all tested positively , alls i can attribute this to is the injectors for 7 and 8, either they are clogged or altogether not working, like i said checked em with the stethoscope and they arent as loud as the rest, the sound is so faint you could even say im picking up the reverberations of the two functioning injectors on the driver side bank two new injectors are on the way, say, it couldnt be the ecm right? i mean if it were, wouldnt all four on that side cease to function?? cause this is MPFI all the injectors for one bank fire at the same time hoe do i check to see if ive got a bad injector connector?

 

A noid light will test the conector and ecm controll of the injector .

 

a noid light? can i make one of those? one last question, im running a 2.5 inch straight pipe with no cats and shorty headers (dont need cats in my state) could the lack of back pressure be causeing it to run rough?

 

A noid lamp can be made from a low watt test lamp . You just need to plug in to the injector wiring harness plug .Let the plug supply power and ground to the test lamp to ck both sides of the ckt . It should flash while cranking and running , and vary with engine load . I don't see the exaust causing your issue . If your pipes go past the cab , that is enough back pressure .

 

Yes, your system injectors are batch fired, so if the failure came from the ECM there would be a 4 that wouldn't fire. If you think there are a couple of injectors clogged you should look into that.

 

Don't EVER set base timing "by ear" with EEC-IV or OBD-II. It will NEVER be right! 10 to 12 BTDC is the limit on SD (speed density) engines (your '89 is SD) and there is very little tolerance outside of that range given the software limitations in the EEC-IV programming. in short, setting outside of this range exponentially throws off everything that the ECM does to optimize engine performance. Set it with a timing light, with the engine at op. temp. BEFORE you begin and the SPOUT connector (shunt) removed... ALL THREE conditions MUST be met. When you are finished, disconnect the battery for about 5-10 minutes to clear all Codes. You can not skip this step or you will have fault Codes all over the place causing no end of headaches. (You just ran the engine without letting the computer control spark timing... the computer doesn't like being left out). Replace the SPOUT connector, restart the engine and take it for a drive for about 30 minutes all over the place.. surface streets, highway, you name it. This will give the computer the chance to "re-learn" the operational parameters of the engine.

As for the injector issue, as was already mentioned, speed density EFI bank-fires the injectors. Best case scenario, you have wiring harness issues at the connectors. or between them and the ECM. ECM failure rate is about 1 in every 100,000.

The "test light" procedure is far more accurate if you utilize an LED. Injectors are fed power for such a brief period of time that most incandescent lamps won't even begin to glow before the circuit is dead again. Don't get me wrong it will work... albeit, seeing it work isn't always easy unless you have a tiny lamp to work with that will respond rapidly. LED's do better at this.

 

ive isolated the problem guys cylinders 8's injector is dead, i checked the resistance on 6 and 7 to use as a basline .14 ohms its what i get when i set my ohm meter to 2K, for 6 and 7, for 8 its dead doesnt read a damn thing i know im making good contact with the probes and everything that injector is without a doubt not functioning