I have a 1987 305 TPI and it has sat for 12 years. When I started it up it ran very rough and then locked up. I found piston #6 with a broken skirt. I have replaced the engine with a 305 TBI block with less than 20,000 miles. I have installed the factory roller cam from the old TPI engine. I also had the heads redone on the TPI engine and installed them on the TBI block. The engine is assembled and running again but it is still running rough. I have replaced all the fuel injectors and flushed out the entire fuel system. I check the vacuum and it is reading around 8 to 10 at idle. Above 2 grand it is around 15 to 18. I have used a scanner and it is telling me it is running lean. I have checked and recheck and I have no vacuum leaks. I have tried the propane test and squirted everything down with carb cleaner with no change.
This is the info from the scanner at idle
Knock=0, Idle air mtr pos=99 steps, Injector Pulse=2.3ms,Throttle sensor=.62v,Manifold air temp=168.4,CCP purge=off,Mass air flow=10,O2 sensor=380mv, battery 14.2v, O2 cross count=74, Block learn=142, Rich/Lean flag=Lean, Integrator=128,Spark adv=24.8, BLK LRN Cell=4 to 5.
The ECCM also never went into a Close Loop with engine temps around 225 degrees. The fans did kick on.

Any help on this would be great. I need to get this project done so I can move on.
Thanks

 

The O2 sensor needs to be switching back and forth from above and below 450mV before the system will go into closed loop. Should hit 200 low and 800 high. Can't remember the minimum cross counts for closed loop on that system but think it's 23 - 27. Scan data will show cross counts.

The single wire sensor has no internal heater and requires exhaust to heat it up to its 600F operating temp. This may require running the engine at 2,000rpm for a minute. They often won't get hot enough at idle. If the O2 voltage doesn't start switching then, first disconnect the sensor and verify .450mV on scan data. Then replace the O2 sensor. If it switches with throttle movement but tends low at idle, there is probably a fault somewhere else causing this. Block Learn is at 142. Max is 156, so it isn't at full rich yet (though 134 is about as high as we want to see). If the O2 sensor is okay and you get it into closed loop, it should be able to get the sensor switching. 142 Block learn means that unless the sensor is just faulty, there is something forcing the system rich.

One thing that's on my mind right now is the AIR system. Be sure that it's switching from the exh manifolds to the cat after the engine has run for a few minutes. If it doesn't switch, the added air at the manifolds will cause the O2 sensor to read false lean and force the fuel trims rich. This can cause the symptoms you're experiencing. Be sure that all the vacuum lines properly connected. Of course the basics. Have you set timing according to the factory spec and procedure? Retarded timing will cause low vacuum.

Are you sure of your valve lash setting? This can be tricky. You need to be sure that the lifter piston is at the top of it's bore at zero lash, then run it down 1/2 turn. Spec is 1 full turn but 1/2 is plenty and preferable for any performance engine. Be sure that the EGR isn't stuck open. Let us know what you find and I'll post back if I think of anything else.

 

Thanks for your great information. I will have more time this weekend to play with the car. The EGR is not stuck open. When I replaced the injectors I took off the EGR and looked at it. When I took it off it was closed. I also took a vacuum pump and checked it's operation. With the vacuum applied the EGR valve would open and when released it would close again. It has been a while since I did the valve adjustment. I think I did 1 turn. I think I will redo the valve adjustment again. That is what I have been leaning towards.
One other question. I also used the distributor from the TBI engine. It was almost new and mine on the TPI was almost 30 year old. I looked up the part numbers at Advance Auto and they were the same. i just want to make sure.
Thanks again.

 

I have adjusted the valves. After I installed the valve covers and torqued the bolts down 1 bolt broke. So now I get the joy of trying to remove the broken bolt. You got to love an easy job that goes wrong.

 

The small body(external coil HEI) would be the same whichever V8 it came from. If you have questions about spark KV or timing, these are easy enough to check. Sorry to hear about the bolt. Hopefully it broke above the casting and you can pull it with visegrips or a stud extractor. The torque on those is what, 65in lbs I think?

 

I thought so. Thanks
For the timing I think I got it right. All you have to do is disconnect the I think the tan wire and set it for 6 deg.
For the bolt braking I did get it out. I used a left handed drill bit and was able to drill it in about an 1/8 inch and then it just spun out. Some times you get lucky. I have it back together but have not start it. Right now the temp outside is 7 degrees. By the way i was torquing the bolts to make sure I did not over tighten them and I still broke that one.

 

I started the car up and it runs better. Now my vacuum is around 15 to 16. I recheck the timing and it is at 6 degrees. At the same time I adjusted the valves I replaced the coil just because I could (I had one laying around). When I goose the throttle it now backfires through the intake. When I shut the car off and try to restart it it acts like a dying battery(slow cranks) I'm going to check all my grounds and starter connections and go from there.

 

a leaking fuel pressure regulator will cause one to run rich. and since you made no mention of checking it . i would start there

 

The backfiring can be caused by a vacuum leak or retarded timing. If an exhaust valve isn't opening you'll get popping from the intake also, but it's different from a backfire. How is you battery and cables? 16" at idle is still low. Expect to see 18-19" at idle from a stock cam engine. Have you checked for codes in the ECM? You may want to look at 02 voltage to see if something is forcing the system lean. Use your timing light to verify that the EST is working. It should read around 20 degrees at idle and swing high with throttle snap. Check to be sure your knock sensor is connected. An knock control fault will cause the ECM to retard timing.