View unanswered posts | View active topics It is currently Thu Mar 28, 2024 3:20 am



Reply to topic  [ 12 posts ] 
 89 IROC - Power Issue - sluggish when warm 
Author Message
Newbie

Joined: Wed May 21, 2014 11:04 pm
Posts: 3
Reply with quote
Post 89 IROC - Power Issue - sluggish when warm
1989 iroc 5.0L. When I first start it after not running for while its got tons of power. After its fully warmed up it seems like its not all there. When its good I could peel rubber in 1rst while rolling no problem but after its hard to even break the back end loose at all. Doesnt seem to be mifiring or anything like that but im wondering what is going to make such a dramatic difference to the power once its warmed up.


Thu May 22, 2014 5:56 pm
Profile
Forum Moderator

Joined: Sat Jun 02, 2007 4:39 pm
Posts: 2433
Location: In the Garage
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Moved to tech section :wink:

_________________
Image

Just rolling with the dog pound...


Thu May 22, 2014 8:04 pm
Profile
Senior Forum User
User avatar

Joined: Sun May 13, 2007 10:48 am
Posts: 984
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Hard to diagnose power loss without data. But a few thoughts to consider; tires grip better as they warm up from driving so it could be as simple as the tires stick and the power feels less because its not spinning and exciting you with the illusion of more power. Also TPI intakes soak a fair bit of heat as as the air temps increase, power output decreases. Hot air is less dense = less power, hence the old sales pitch "cold air intake"

But there are a host of other technical issues that might be at play here as well that are totally legit. Maybe your ign system is breaking down and/or your getting some misfire or your engine is tired and loses compression when it heats up. Speaking of which just about the WORST thing you can do to a car is lay into it when its cold. That'll wreck your engine faster than anything else will.

Perhaps its time to visit a shop capable of performance tuning? With TPI these days, that may prove a bit of a search. Hope this info is of some help

_________________
1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

89 R7U 1LE Players Challenge car all stock.


Fri May 23, 2014 9:54 am
Profile
Senior Forum User
User avatar

Joined: Sun May 13, 2007 10:48 am
Posts: 984
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Memory jogging here. Unplug your MAF and try it again to see how it runs. It wont hurt anything to run it that way and if its noticeably better? Time for a new MAF. K&N filters?

_________________
1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

89 R7U 1LE Players Challenge car all stock.


Fri May 23, 2014 10:18 am
Profile
Senior Forum User
User avatar

Joined: Mon Feb 01, 2010 12:26 pm
Posts: 220
Location: Ottawa
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Do a search on putting heat sink compound under the ignition module in the distributor. When it gets old the stuff dries out and lets the module overheat and causes ignition issues. Pretty common an the tpi's from what I recall.

_________________
86 IROC
LQ4/T56/3.50 8.8 (next step..TC76)
Build thread: http://ls1tech.com/forums/conversions-hybrids/1819001-1986-iroc-turbo-lq4-t56-build-ac.html
Formerly 95 LT1 [LE2.2]/T56/4.11 9 Bolt..12.6@114MPH


Fri May 23, 2014 10:51 am
Profile
Newbie

Joined: Wed May 21, 2014 11:04 pm
Posts: 3
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Thanks for your thoughts. I dont lay into the car when its cold. I say cold as in the first few kilometers of driving but I always let it warm up before going. I dont think its the tire traction issue. The feel of the car is completely different. I used breaking the tires loose as an example of the power difference but aside from the tires not peeling it still is a lot slower. I will try the MAF today. Im also thinking coolant temp sensor could be the issue. I noticed one day the temp gauge wasnt working at all but since then it has been working but if its the same sensor that sends reading to the computer then it could be the issue.

Also I just replaced the ICM and and new heat sink with it for a previous no start issue and was hoping that would solve this problem as well but its the exact same as it was even with new ICM.


Fri May 23, 2014 10:54 am
Profile
Forum Moderator
User avatar

Joined: Thu Mar 17, 2005 10:28 pm
Posts: 5900
Location: Center of the Universe
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
I had an issue similar with our old 90 Iroc, eventually it wouldn't even start until it sat for a couple hours, turned out to be the injectors. You might want to get them cleaned and tested, if they are still the stockers then they are pretty old now anyways


Fri May 23, 2014 1:52 pm
Profile
Senior Forum User
User avatar

Joined: Sun May 13, 2007 10:48 am
Posts: 984
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
^ Yep. Whole fuel system in fact is in question. Was going to walk the easy road first, see if the MAF trick works etc. then escalate as nec. Check fuel pressure at the rail when its cold and running good and when its hot and not running good. Think your way through this by process of elimination. The mech training 101 is such

Got fuel?
got spark?
got compression?

Three criteria with hundreds if not thousands of possible root causes.

_________________
1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

89 R7U 1LE Players Challenge car all stock.


Fri May 23, 2014 2:14 pm
Profile
Newbie

Joined: Wed May 21, 2014 11:04 pm
Posts: 3
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
New to this forum and already first post has great responses and help so thanks so far for the replys.
I tryed unplugging MAF not really any diff. Changed CTS and no difference but gauge doesnt seem to be reading properly even with new CTS. Maybe not related to my problem but ya... tomorrow I will measure fuel pressure and see what happens.


Sat May 24, 2014 12:59 am
Profile
Forum Moderator
User avatar

Joined: Thu Mar 17, 2005 10:28 pm
Posts: 5900
Location: Center of the Universe
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Iroc wrote:
New to this forum and already first post has great responses and help so thanks so far for the replys.
I tryed unplugging MAF not really any diff. Changed CTS and no difference but gauge doesnt seem to be reading properly even with new CTS. Maybe not related to my problem but ya... tomorrow I will measure fuel pressure and see what happens.


there are 2 temp sensors, the one in the head is for your gauge in the dash, if it was bumped or loose then that would most likely be why your gauge wasn't reading, I am tired so cant remember where the other one is off hand, I think its on the TPI intake manifold at the front, I assume that is the one u changed, hopefully someone else pipes in

_________________
http://forums.kwmuscle.com/viewtopic.php?t=4238&start=0 Laughing at dumb dumbs since Oct 03/11
Alex IROC Z-28 wrote:
Ohhh lord....here we go..... Hawk one time kicked Chuck Noris ass so bad that Chuck Noris filed for Workers Comp......

Image


Sat May 24, 2014 11:29 am
Profile
Senior Forum User
User avatar

Joined: Sun May 13, 2007 10:48 am
Posts: 984
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
Change thermostat

_________________
1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

89 R7U 1LE Players Challenge car all stock.


Sat May 24, 2014 11:34 am
Profile
Forum Moderator

Joined: Fri Mar 18, 2005 6:54 am
Posts: 1840
Location: ingersoll
Reply with quote
Post Re: 89 IROC - Power Issue - sluggish when warm
The cold temp sensor is on the underside of the plenum. The first temperature sensor for the gauge is on the drivers side head. The one for the computer and fans i believe is on the intake right near the front under where the thermostat goes. Also dont be afraid to change out the oxygen sensor. Alot of times even if they dont throw a code they do start missreading as they get older. This is one of those items where cheap is not better.

_________________
355, trickflow heads, comp cams roller cam, compcams rollertip rockers. First fuel injection, t56, hooker headers, dynomax exhaust.


Sat May 24, 2014 2:03 pm
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 12 posts ] 

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group.
Designed by STSoftware for PTF.