ChevyK10

I've got a 350 TPI in my 1976 K10, which was originally taken out of a 1992 Camaro. I recently replaced the engine due to the cylinder #6 piston breaking. I have probably put at most 20 miles on the new engine. Since replacing the engine I've been struggling with an issue where bank 1 is running particularly cold, and bank 2 is running hot. I've got long tube headers, true dual exhaust, some no name mufflers, and both cats have been cut out. Bank 2 is spitting a good amount of soot out of the exhaust, and the exhaust gas and header is significantly hotter than bank 1. The exhaust leaving the tailpipe of bank 1 does not feel like it has much force to it, and doesn't even feel warm, while the the exhaust coming from bank 2 feels consistent, strong, and hot. The engine is idling at a little less than 1,000rpm in park. The idle is steady and the timing is set to 6*btdc. The fuel pressure at the rail is around 40psi at idle, it was a little lower before I replaced the FPR, which let go a few weeks after the engine was replaced. I ohmed out all of the injectors (which were replaced at the same time as the engine, bought from Napa) and those all seemed good. I have tested all the injector connectors with a noid light and each of the connectors flashed at a consistent speed and brightness. I am not getting any codes. I've unplugged the injectors one by one with the engine running and the idle responded to each, some more aggressively than others, but I can't feel a miss. I measured the temperature of each tube of the headers with a temp gun after 5 or 10 mins of idling. The temperatures were:
Cyl1 115* Cyl2 195*
Cyl3 133* Cyl4 325*
Cyl5 173* Cyl6 232*
Cyl7 131* Cyl8 146*

I think that a part of the difference in header temperatures is due to the fact that I do not have the driver's side wheel well installed, which is leaving that side basically free from wind obstruction, and the fan is pushing more air to that side (my shop foreman actually suggested that), but that doesn't explain a difference in a/f ratio bank to bank. I understand that my a/f ratio is being determined only by the exhaust coming from bank 1, so my overall engine performance is being determined by bank 1.

I do not have any experience working on these engines, other than what I have done with this one. So maybe this is normal operation and I'm being over analytical, but I have put a lot of time and energy into this truck and I think I can make it run better. Here is what I've done to try and fix this problem:
-ECM and PROM from Tuned Performance (the old PROM was tuned for mild performance and the ECM looked pretty questionable)
-Resealed the entire intake manifold due to an oil leak from the back of the manifold after engine replacement
-All new vacuum lines
-New CTS and pigtail (was reading -50* when I got the truck)
-All new ignition
-New heated 02 sensor

Tomorrow I'm going to pull my plugs again, read them, and double check the gap. If anyone can think of anything I haven't thought of, or has literally any insight to point me in the right direction I would be extremely grateful. I'm getting really frustrated and discouraged.

I also really need to get a OBD1 scan tool or a cable to hook up to my computer so I can get a better idea of what is going on with my engine data, if anyone has any suggestions I would be really appreciate that as well.

Thanks!

GeneralDisorder

iTrader: (1)

Injectors? What are they? Sounds like you need to replace them or test them at the very least.

GD

ChevyK10

Tuned Performance

iTrader: (92)

GeneralDisorder

iTrader: (1)

Well - thing about TPI is that it bank fires the injectors - so all 8 injectors fire at the same time and if they are flowing the same amount of fuel then the combustion event is going to be very similar across all cylinders (temperature wise).

You say that each cylinder makes a difference if you unplug the injector so that would seem to confirm that ignition is ok - and really that's a fairly binary scenario - it either works or it doesn't. So unless it's doing a lot of misfiring.....

Looks like cylinder 4 and 6 are excessively lean. Given the fuel pressure, the fact that the idle changes when you unplug the injectors on all cylinders...... that would point to injectors not flowing equally.

Check for vacuum leaks as that can lean out some of the cylinders also. But the unknown nature of the injectors is seriously suspect. I wouldn't even consider using injectors from a parts store for this application. Call SouthBay Injector and get some Delphi's or Bosch III's if you plan to tune it again.

GD

Aviator857

The stock wiring on the TPI each bank has a fuse. Get a set of noid lights and see if each injector is getting a pulse.

ChevyK10

I didn't fiddle with this issue before swapping the engine or injectors. I was pretty wet behind the ears in regards to working on cars when I bought the truck, so I'm not sure if I was experiencing this problem before the work started. I did notice more exhaust coming from bank 2 before replacing the engine but I figured that was due to a chunk of piston #6 being stuck in the cat. The only parts that remain from the old engine are the intake assembly, fuel rail (both were cleaned and inspected thoroughly), the wiring harness, tps, and intake air temp sensor. Thank you for your reply!

ChevyK10

My idle isn't really indicating a vacuum leak, which is good. I have searched far and wide for any vacuum leaks with carb cleaner and soapy water. Replaced all my vacuum lines and resealed the intake twice. If I were to have a vacuum leak causing 4&6 to run lean would an internal vacuum leak in the intake be a possibility? I would like to get this thing into work to give it a proper smoke test and get some time in with other better diagnostic tools and opinions from co-workers, but I'm concerned about damaging something with my current problem. It's about a 15 mile drive to work, is that a valid concern, or should I just drive it in?

I wish that I would have known about what you said in regards to injectors earlier. If I need to replace the injectors again, then so be it. I've actually got a coworker with a set of ford yellow tops he said I could have, they just need to be cleaned. How can I go about testing the flow of the injectors? Is it something I can do on my own, or is it something that should be professionally done? Thank you for your help.

ChevyK10

Already done, included that in my original write up. Thanks!

GeneralDisorder

iTrader: (1)

You can use a simple device like this:


What this does is sends a pulse to the injector you connect it to, and that pulse is very accurately timed. So you watch the pressure drop from that timed pulse on each injector and if some cause more pressure drop than others they are not all equal.

You have to cycle the key between each test so you are starting with the same pressure behind each injector. Sometimes having an assistant quickly clamp off the return as the pump cycle stops is helpful for systems that want to bleed down quickly.

GD

TORN

iTrader: (17)

https://www.thirdgen.org/forums/engi...ch-3-24lb.html

I would jump all over these if I needed injectors. Really good price.

GeneralDisorder

iTrader: (1)

That's a great price. I run those exact injectors on my current daily. Very nice with tuning (but they do require tuning for sure). I have mine scaled at 22.5 lb with proper voltage offsets.

GD

Aviator857

Ahh missed that. Could you have a blockage or kink in the fuel rail that limits fuel flow to one bank? I'll read through your post in more detail and see if I think of anything.

Aviator857

Is the engine a roller cam? Solid or hydraulic lifters?

Personally I would pull valve covers and check the valve train. If for example valves not fully opening.

The other thing is you should put a h or x pipe on the exhaust, this will help balance exhaust pressure bank to bank, unless a muffler is clogged this will not solve the issue but it's good to do.

Also worth swapping injectors bank to bank to see if the problem moves. Same for spark plugs but make one change at a time.

Verify each spark plugs is sparking.

I know you said intake was inspected but is it possible the gasket is wrong or backwards on one side?

Long shot, is it possible a shipping cap was left on some of the injectors and melted off?