I have been driving my swapped 90 for two years now with almost no issues at all but lately its started to act strangely. It will fire up and idle perfectly but as soon as you give it any throttle it bogs badly. so far in effort to find the issue I have replaced the cat, plugs , wires, tps,fuel pump, replaced the C.o.r and eventually bypassed it all together because I was not getting a prime cycle from the ignition and nothing has helped even the slightest bit. while checking my live stream data the ect looks to be reading correctly but randomly throws a speed sensor code ( my sp1 wire was tied into the combo meter during the swap). I currently have both o2 sensors disconnected and that made no difference.
I am sure I have over looked something simple but I am at a lose .. throw some ideas at me

thanks

 

Try cleaning the throttle body. Is it running in open loop or closed loop?

 

I have cleaned both the throttle body and the mass air thoroughly. but im not sure what you mean when you ask if its running in open loop or closed loop.

if you mean has it thrown code after all these attempts,.. no I have not been able to get the truck to go more than 50 kph for some time now

 

You said you were looking at live stream data. You should have been able to see if the engine was running in open loop or closed loop.

 

Tried fuel filter? Will it rev to redline in neutral?

 

new fuel filter as well .. it will rev up to 5k but sounds a bit off when you do. I just took the truck for a run with the o2s unplugged and got a p0125 and p0135 as you would expect with unplugged o2's

 

the only thing I can currently think of that I have not tried is injector cleaner. off to the store..... again

 

If one or more of your injectors are clogged the engine would miss

 

there is no miss fire ,.. slight bogging when starting but thats all. idles around 650 but smooth but bogs as soon as accelerate

 

Sure sounds like a fuel issue, interested to figure out the problem

 

so I ran injector cleaner and it made no difference at all. So I started going through the live data again and noticed that it is retarding the timing back to -40* I was under the impression the 3.4 would only retard the timing to -12*. anyone run into this in the past ..

I

 

.. have you checked your fuel pressure ? sounds like fuel pump to me


.

 

brand new fuel pump with perfect pressure

 

ok I found a vac line thats obviously been off for a long time under the intake. while im in there does anyone have a good method for testing the fpr with out the truck running?

 

Fpr means fuel pump relay?

Have you checked your intake boot for large rips or splits? I remember reading someone else had this issue and there was a gaping hole in the intake boot causing unmetered air into the motor. Worth a shot

 

sorry no I meant the fuel pressure regulator,... I've gone over the intake tube and it looks to be crack free

 

After checking the timing marks and noticing that the cam marking and crank markings were not quite right I removed the crank pulley and found that the crank timing gear has worn on the woodruff key and is now moving freely back and forth one whole tooth (1/4") but will not freely slide off of the crank shaft. I've never seen anything like it before but I suspect this is the root of my problem.