hi everyone, i hope somebody would be able to help me out with getting my lq9 to rev correctly. so i just swapped a lq9/4l80 into my 1988 caprice, it idles fine at about around 850- 900ish rpms. when revving normal or fast it falls on it face and just goes flat like if it was idling but if you slowly rev it it’ll rev higher but still has issues. has p0650 code. fuel pressure is 58psi at idle and while revving. its DBC, using stock truck harness/ fuse block. thanks for the help in advance

 

You didn't tell us what year LQ9, but if it came with the dbw throttle body there needs to be some work done to the PCM and running some wiring to get it to work correctly.
Here is some info DBW to DBC

 

its a 2003 lq9 for a escalade. i took the pcm to get flash an base tuned and switched to DBC, the sensor and connectors been wired in for the DBC throttle body. im thinking it my have something to due with the tune.

 

here is some reference information from Brendan @ lt1swap.com
A treasure trove of info !

 

could a leaking rear main seal/cover gasket cause a vacuum leak which would make it not want to rev?

 

No ,it will not.

 

would it cause low crankcase pressure?

 

Doesn't sound healthy with the squeaking and tapping noise. Maybe it's just the Youtube audio but it sounds like it's struggling mechanically when you blip the throttle. Escalades come with the 4L60 and you posted you're running the 4L80. Do you have the correct flexplate and did you have clearance between the converter and flexplate?

 

man i hope nothing is internally wrong with my engine. yes it has a 4l80 the pcm had been programmed for the 4l80 and also running the correct flexplate. but it still makes noise even with the transmission removed.

 

heres more video of the noise

 

can you hook up a scanner to the obd2 port and see the TPS values ? Are all other sensors reading in spec ?

 

its not throwing any engine codes. but tomorrow i can check it out, what range should the sesnors be in?

 

TPS = 0.45v-0.79v closed and just under 5v WOT seems to work in most applications. TPS % MUST RETURN TO 0.00% when throttle closed.

 

ok i ill check it out later today and check back in with the reading. thanks

 

i checked the voltage for the tps and its reading flat, doesn't go up when i move throttle

 

how many wires in the TPS connector?

 

 

3 wires
so i just found out that cylinders 2,3,5 and 8 aren't firing

 

I take it the voltage reading was less than 1 volt and flat? that explains why the engine doesn't rev up and wants to stall when you open the TB quickly. The PCM isn't receiving the needed higher voltage input on the signal wire. Is there 5volts on the TPS reference wire?

 

yeah it was completely flat, i checked it with a scanner. tomorrow ill check it with a multimeter, thanks. by chance do you know why my engine is running on only 4 cylinders?