HomeHome  PortalPortal  CalendarCalendar  GalleryGallery  FAQFAQ  SearchSearch  RegisterRegister  Log in  

Share
 

 l05 powerloss/light idle surge

Go down 
AuthorMessage
benn

benn

Posts : 557
Join date : 2011-12-22
Location : Ontario, Canada

l05 powerloss/light idle surge Empty
PostSubject: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeThu Aug 15, 2013 9:13 pm

My '92 Rmw has been having issues for a while. the main one is a severe/intermittent loss of power. usually between 1500 and 2000 rpm is when the power loss is exceptionally noticeable. i dont want it to sound like a beat the crap out of my car, but it wont even chirp the tires from a dead stop. if you apply about a 1/4 throttle it does okay putting you back in your seat but as soon as it touches 1500 pm it falls flat on it's face. after 2000 rpm it sorts itself out and does fine.
also, the idle in nuetral/park surges a bit by about 200-300rpm at most. it idles smooth in gear.

heres some info:
its has had a recent tune up (plugs, wires, cap/rotor)
it also has a new ignition coil in it.
the EGR has been disconnected long ago and capped off
new coolant temperature sensor
new O2 sensor
no codes have been thrown
it passed an emissions test recently

maybe the timings a bit off??

any insight guys?
Back to top Go down
phantom 309

phantom 309

Posts : 5811
Join date : 2008-12-28
Age : 109

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeThu Aug 15, 2013 9:18 pm

make sure you have good fuel pressure clean filter etc,.could be a vacuum leak,.
tweak the fuel pressure spring on the injector pod,.
Back to top Go down
benn

benn

Posts : 557
Join date : 2011-12-22
Location : Ontario, Canada

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeThu Aug 15, 2013 10:06 pm

thanks nick,

forgot to mention it has a new fuel filter. any tips for tweaking the FP spring on the injector pod? i have no experience there...
Back to top Go down
Fred Kiehl

Fred Kiehl

Posts : 5196
Join date : 2009-11-13
Age : 70
Location : Largo, FL 33774

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeThu Aug 15, 2013 10:24 pm

The issue is probably the pump hose in the tank. If it has split, it can cause the idle surge, as well as acceleration issues. when the pump twists the hose, it opens the split, and the fuel pressure drops. I had a similar issue when I got my 92 OCC. It did not throw a code. Tweaking the spring will not help you if the issue is the hose. The easiest way to measure the fuel pressure is to install the fuel lines from a 91 or 92 FW with a Chevy engine...they have a Schrader valve port on them.

If you are interested in increasing the fuel pressure, there are some split rings for key chains that will fit over the adjuster in the regulator, and large enough that the spring will sit on top of it.. I am not sure what the diameter is, but I bought one a couple of days ago.
Back to top Go down
jayoldschool

jayoldschool

Posts : 2544
Join date : 2009-06-14

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeThu Aug 15, 2013 11:57 pm

ICM might be a good part to throw at it since you've done the other ignition stuff.
Back to top Go down
Gastt

Gastt

Posts : 525
Join date : 2010-07-30
Age : 31
Location : Treasure Coast, FL

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 7:00 am

I think power loss was a factory option.
Back to top Go down
lakeffect
Moderator
lakeffect

Posts : 3889
Join date : 2009-08-18
Location : Rochester NY 14621

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 8:26 am

option PL1

Since it's surging at idle as well, I'd agree with a vacuum issue.  Part of the surge tends to come from the ECM trying to compensate the rpm via air flow.

(I'm trying to remember if the 92's had an Idle Air Control (IAC) of some sort on the TBI cars. I know it was part of the LT1 setup, under the throttle body.  It's been years since I played with TBI.)

Anyway, if so, it is usually how the ecm tries to level out idle by running the IAC  shaft in and out. Once again, the cause could be a vacuum issue that the IAC is fighting to control via changing what air is allowed in.

I can see Fred's point about the fuel lines, What does it do above 2000 rpm? If there's not enough fuel I'd suspect the farther up the rpm goes the more starved the engine becomes. It should be falling on it's face at 4000 rpm it that's the case.


Dave
Back to top Go down
phantom 309

phantom 309

Posts : 5811
Join date : 2008-12-28
Age : 109

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 10:50 am

the fuel rate will over come a vacuum leak at higher throttle openings, because as we all know the vacuum drops right off as the throttle is opened,.
vacuum leaks are most noticeable at part throttle,.
Back to top Go down
Olds Weighty Eight

Olds Weighty Eight

Posts : 1061
Join date : 2011-05-15
Age : 52
Location : Memphis, TN

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 12:57 pm

lakeffect wrote:
(I'm trying to remember if the 92's had an Idle Air Control (IAC) of some sort on the TBI cars.  I know it was part of the LT1 setup, under the throttle body.  It's been years since I played with TBI.)
They do. Same IAC valve as my Grand National by the way.

[You must be registered and logged in to see this link.].

[You must be registered and logged in to see this image.]
Back to top Go down
http://www.lakelandraceway.com/friends_garage
Guest
Guest



l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 1:00 pm

I need the pigtail for the IAC on mine. It's all kinds of fubar'd.
Back to top Go down
Cadet57

Cadet57

Posts : 3047
Join date : 2010-04-13
Age : 31
Location : Chicopee, MA

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 6:18 pm

jayoldschool wrote:
ICM might be a good part to throw at it since you've done the other ignition stuff.
Agreed. I had to replace them each time I did a tuneup on our TBI's.
Back to top Go down
lakeffect
Moderator
lakeffect

Posts : 3889
Join date : 2009-08-18
Location : Rochester NY 14621

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 8:22 pm

phantom 309 wrote:
the fuel rate will over come a vacuum leak at higher throttle openings, because as we all know the vacuum drops right off as the throttle is opened,.vacuum leaks are most noticeable at part throttle,.
Thanks for the additional clarity Nick.

Dave
Back to top Go down
benn

benn

Posts : 557
Join date : 2011-12-22
Location : Ontario, Canada

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 16, 2013 8:28 pm

Gastt wrote:
I think power loss was a factory option.
came standard Wink 
Back to top Go down
benn

benn

Posts : 557
Join date : 2011-12-22
Location : Ontario, Canada

l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitimeFri Aug 23, 2013 9:13 am

Well I haven't had time to work on the problem. I've really been concentrating on what exactly happens when the gas is applied though. Like I said the problem is intermittent but when it happens you can hear the engine bog usually around 1500 - 2000 rpm. When gas is applied in this range the rpm doesn't change either. If you floor it durring the bogging or at least give it enough gas to kick down out of overdrive, it will accelerate normally.

Possibly related, I had to use the defrost this week and noticed my HVAC is screwed. Hardly any air moving when the fan is on full. When the HVAC is off I can still feel heat coming from the floor vent. Correct me if I'm wrong, but I think vacuum for the HVAC is taken off the back of the TB. I checked the vacuum connection there and it was fine...

I'm thinking my possible problem(s) are:
TPS
IAC
big azz vacuum leak
Fuel pump line in tank is split.


Back to top Go down
Sponsored content




l05 powerloss/light idle surge Empty
PostSubject: Re: l05 powerloss/light idle surge   l05 powerloss/light idle surge Icon_minitime

Back to top Go down
 
l05 powerloss/light idle surge
Back to top 
Page 1 of 1
 Similar topics
-
» Image 'light up' effect with mouseover
» Navigation Bar - Gradient Light Blue

Permissions in this forum:You cannot reply to topics in this forum
GM Longroof Forum :: Longroof Tech :: Engine-
Jump to: