Throttle Tip-In Issues
Thread Starter
Racer
Joined: May 2003
Posts: 304
Likes: 1
From: beaverton oregon
Throttle Tip-In Issues
95' AT 85000 miles...
The car is getting so damned close to what I want...
Here's the deal. Finally got the exhaust system all welded up and the headers so they don't touch the frame. Car revs insane starting at about 2800 to 6100... Very pleased. Overall, very drivable...
However, there are weird things going on with throttle tip in from idle.
1-5% throttle tip in, all is well. Very smooth.
5-30% throttle tip in, it will occasionally hesitate and act like it wants to die. Frequently, I also get an exhaust pop. Once it gets over 2000 RPM, its fine.
30% and above throttle tip in, no hesitation, occasional pop, but once over 2000 RPM, its fine.
She also intermittently idles like crap, usually after starting when warm. Again, all is well over 2000 RPM.
I guess one solution would be to get a 2500 stall converter (never let it get below 2000 RPM)
Any ideas on this? TPS? Vacuum? Can't imagine its the IAC. O2 sensors are pretty new. Opti is VERY new. No codes...
Any help would be appreciated...
The car is getting so damned close to what I want...
Here's the deal. Finally got the exhaust system all welded up and the headers so they don't touch the frame. Car revs insane starting at about 2800 to 6100... Very pleased. Overall, very drivable...
However, there are weird things going on with throttle tip in from idle.
1-5% throttle tip in, all is well. Very smooth.
5-30% throttle tip in, it will occasionally hesitate and act like it wants to die. Frequently, I also get an exhaust pop. Once it gets over 2000 RPM, its fine.
30% and above throttle tip in, no hesitation, occasional pop, but once over 2000 RPM, its fine.
She also intermittently idles like crap, usually after starting when warm. Again, all is well over 2000 RPM.
I guess one solution would be to get a 2500 stall converter (never let it get below 2000 RPM)
Any ideas on this? TPS? Vacuum? Can't imagine its the IAC. O2 sensors are pretty new. Opti is VERY new. No codes...
Any help would be appreciated...
Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
Sounds just like what has been happening with my 95 but I don't have the mods you do. Opti and plugs and wires are only about 2 years old but I found bad corrosion on the wire that plugs into the coil (from the opti). Cleaned the corrosion and it ran great for about 2 days but now runs just like yours--stumbling idle, stumbles on hard acceleration from a stop, feels like someone is turning the key off at about 1/3 throttle, then fine at higher revs. As I posted elsewhere, you will find a tremendous variety of opinions on what could be the problem but most will probably say opti (which may not be the case).
Thread Starter
Racer
Joined: May 2003
Posts: 304
Likes: 1
From: beaverton oregon
gbody: tjwong has taken a shot at it previous to the exhaust being welded up... plan to go back soon now that its actually together...
DougSilver: this rings true. I also looked at the old posts where you discussed this. With all the mods and recent opti replacement, i have plugged and uplugged everything. time to recheck my work. any progress on your stumble?
crheinish: will also try this this weekend
BrianCunningham: Replaced about 5000 miles ago, should be okay... but i am wondering about fuel system... bad injector? Still, seems odd that it only occurs in that certain throttle body position/rpm range...
BTW, does anyone know an easy way to check vacuum? was wondering about that, too...
DougSilver: this rings true. I also looked at the old posts where you discussed this. With all the mods and recent opti replacement, i have plugged and uplugged everything. time to recheck my work. any progress on your stumble?
crheinish: will also try this this weekend
BrianCunningham: Replaced about 5000 miles ago, should be okay... but i am wondering about fuel system... bad injector? Still, seems odd that it only occurs in that certain throttle body position/rpm range...
BTW, does anyone know an easy way to check vacuum? was wondering about that, too...
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
[SNIP=TankerVette]gbody:
BTW, does anyone know an easy way to check vacuum? was wondering about that, too...[/SNIP]
Pick up a vacuum gauge at any auto parts store, they're cheap. It should come with instructions and a fexible hose.
Just plug the vacuum gauge into a vacuum source on the engine and take a reading. I use a block off hose nipple on my power brake booster since it has a direct connection to the plenum.
The reading should be steady, but actual number that registers depends on a few variables, such as the duration/overlap of the cam, etc.
Jake
BTW, does anyone know an easy way to check vacuum? was wondering about that, too...
[/SNIP]Pick up a vacuum gauge at any auto parts store, they're cheap. It should come with instructions and a fexible hose.
Just plug the vacuum gauge into a vacuum source on the engine and take a reading. I use a block off hose nipple on my power brake booster since it has a direct connection to the plenum.
The reading should be steady, but actual number that registers depends on a few variables, such as the duration/overlap of the cam, etc.
Jake
Melting Slicks
Joined: Mar 2003
Posts: 2,472
Likes: 0
From: Toronto ONTARIO
i had a rare problem that had some of the same smyptoms you are describing. on the front of the waterpump.. the coolant temp sensor. unplug it anc check to see if the terminals are clean. believe it or not my car stumbled and would die on me when it warmed up.. i took it to my friend to look at.. he plugged in the scan tool and the temp showed -43 celcius or something like that.. cleaned the terminals.. and bang.. car ran 100%.
might not be your problem but i suggest you and others who read this clean that plug while theyr'e in there. takes a few seconds and can save the month of headaches i went thru!
might not be your problem but i suggest you and others who read this clean that plug while theyr'e in there. takes a few seconds and can save the month of headaches i went thru!
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