Hello all, new member here hoping for some insight and direction. I recently purchased a 1985 K5 Blazer that somebody had swapped a 90-92 SD Tpi setup into (poorly I might ad).The problem is the motor runs very rich to the point of black smoke along with the gas station smell out the pipe. So far I have replaced transmission with new 700R4, new 22# Bosch injectors from SouthBay, CAI setup, fixed piles of bad wiring, new plugs/wires/and distributor, reman heads casting 191, new fuel pump/filter, headers with dual 2.25" into single 3" Flowmaster exhaust,

So far for diagnosis I have ohmed the sensors and injectors everything checks out, reset IAC and TPS checked and rechecked plug wire arrangement, multiple checks setting base timing to 0* with EST wire unplugged, to the best of my knowledge no vacuum leaks - although at idle only get 15-16 on the vacuum guage consistently. . Checked fuel pressure at key on 41psi but begins to fall immediately pinched off return and pressure holds so have a new fuel pressure regulator going in tomorrow. If the regulator doesn't fix what else can i try?

Compression is even at 112-114 psi on all cylinders, seems low to me, leak down test shows 14-15% loss across the cylinders Could the different heads require a tune of the ECM, or the compression and ring wear be causing?

I have just acquired an ALDL connector and have installed TunerPro RT so far haven't gotten very far with this other than to see no codes being stored.

Any thoughts or suggestions would be greatly appreciated.

Thanks in advance for your replies.

 

Did you put a heated o2 sensor in? That's usually a requirement with headers. Also base timing should be 6 degrees unless you've got something special going on.

 

My bad timing was set to 6* not 0* with est unhooked. I was wondering about heated o2, I have mid length headers with o2 mounted before the collector would it make that much difference? Will have the new fuel pressure regulator installed today to see if that helps.

 

The heated O2 is really to keep the O2 element hot so the ECM stays in closed loop. Other than that it functions exactly like a non-heated.

Sometimes its necessary with headers at idle since it can cool off and fall our of closed loop.

If you're youre not falling out of closed loop then it's not necessary.

What kind of injectors did you get? Bosch-III?

15-16" inhg idle vacuum suggests a non-Stock cam. When you get TP data, post up a csv file export and we can take a look at it.

 

Injectors are Bosch 3 remans from southbay, So far I've only managed to see it hit closed loop very briefly then falls right back into open loop, at least parked, I haven't had a chance to view while driving. As soon as i can get logging with TP I will definitely post. I appreciate the reply's, this is my first run at fuel injection so definitely learning as I go.

 

I'm suspicious of vacuum leaks, try capping off all your accessories and see if you can get more vacuum on the gauge.

 

Bosch 3 probably will require some tuning (even if the flow rate is the same). Can do a search on them here as they've been discussed at length.

If you're falling out of closed loop at idle, then yeah, probably need a heated O2.