90 Q45 starts and idels fine but will not rev past 2000 rpms

[Ls1_2002]

Hello. My Q45 sat for nearly two years in need of coolant & vacuum hose replacements below the manifold & an occasional misfire. I replaced all hoses and intake o rings, put it back together and fired it up. it started fine was idlingrough & would not rev past 2000 rpm . It seems to pop if you try to rev it up. It will now idle good without bucking but still will not rev past 2000 rpms. I have checked connections spayed contact cleaner . Replaced fuel pump with one from the wrecking yard . Checked the fuel pump module for burn marks. My next on the list is to get codes , check fuel pressure, purchase a used maf since many threads point to the maf for symptoms like mine. Any information would be greatly appreciated. Nothing would be more fun than whooping a few more mustangs , camaro's . I own a 94 Lt1 Formula and the Q45 used to run it down from 40 mph on . Thank you for your time .

[Q451990]

I think you're on the right track trying a known working MAF. Does it stop at 2000 RPMs on the tach like there's something electronic telling it to do so? If so, it's probably in "safe mode" for any number of reasons.

Good luck!

Heath

[Q45tech]

Study FSM, CAS High mode Fail Safe stops revs at 2,000 rpm. Probably just corrosion at one of 2 connectors.

[Ls1_2002]

Thank you for the help with my Q45. If i unplug my maf while running it does not change rpms too much. However when i unplug the box located on the throtle body it does absolutely nothing . What is the purpose of this strange box ? It seems odd it would do nothing . Thank you in advance for any help!!!!!!!!!!!!!

Modified by Ls1_2002 at 5:08 PM 10/22/2007

Modified by Ls1_2002 at 5:09 PM 10/22/2007
Modified by Ls1_2002 at 5:10 PM 10/22/2007

[maxnix]

Study FSM.

[Q451990]

Thank you for the help with my Q45. If i unplug my maf while running it does not change rpms too much. However when i unplug the box located on the throtle body it does absolutely nothing . What is the purpose of this strange box ? It seems odd it would do nothing . Thank you in advance for any help!!!!!!!!!!!!!

That is your throttle position sensor. Please, please, please, don't adjust anything on the throttle body! There are a lot of fun looking screws and springs on there - but treat it like your sister-in-law - don't touch!

Heath