LQ4/ 1995 Impala SS Problems
LQ4/ 1995 Impala SS Problems I've just about completed my swap (LQ4/4L60E into a 1995 Impala SS) minus AC.
Problem #1
I had my PCM programmed by Speartech for 3.08 gears (which it currently has), and my speedometer is still reading like double what It should.
Problem #2
I'm also getting an extremely high idle condition, like anywhere from 900 to 3000 rpm. Sometimes It'll start up and act like it wants to die, but I guess I'ts just going through its Idle relearn Procedures because It'll idle good for about 5 min then it starts to rise. I've checked for possible vacuum leaks, replaced Intake manifold Gaskets,and it has a brand new IAC. I can't think of anything else that could be causing it to slowly rise, because a vacuum leak would be instantaneous, right?
I'm using Street and Performance type 3 headers, 2.5" exhaust all the way back, FAST 78MM TB, LS1 intake Manifold, Street and Performance AIR plug and Truck accessories. The Motor is stock otherwise.
Problem #1
I had my PCM programmed by Speartech for 3.08 gears (which it currently has), and my speedometer is still reading like double what It should.
Problem #2
I'm also getting an extremely high idle condition, like anywhere from 900 to 3000 rpm. Sometimes It'll start up and act like it wants to die, but I guess I'ts just going through its Idle relearn Procedures because It'll idle good for about 5 min then it starts to rise. I've checked for possible vacuum leaks, replaced Intake manifold Gaskets,and it has a brand new IAC. I can't think of anything else that could be causing it to slowly rise, because a vacuum leak would be instantaneous, right?
I'm using Street and Performance type 3 headers, 2.5" exhaust all the way back, FAST 78MM TB, LS1 intake Manifold, Street and Performance AIR plug and Truck accessories. The Motor is stock otherwise.
Hi.first off all you must check if there is any DTC codes from the ECU. you need a programmer to read it. I use EFI Live. This tool or an equal tool is a must for a engine swap. if not, this is going to be guessing.
On The Tree
Joined: Jan 2007
Posts: 116
Likes: 0
From: Florida
Unplug your MAF while its running and if idle goes to normal, bada bing. I've also heard people adjust their throttle blade, if drive by cable, there's a set screw under throttle cam/pulley thats a star bit, I believe T15. I'd start with the MAF.
As far as the speedo.. I think it has to do with the pulses per mile. I know my car needs 4000ppm for the speedo to read right. Are you hooked to the right wire? Just something to check.
I've tried unplugging the MAF, runs like ****, like it should. I have a FAST 78mm Throttle body, and adjusted the throttle blade after resetting the the IAC, takes a while, but still goes sky high. Turn it off, then back on, same thing.
I currently have a 95 Camaro Z28 cluster in my car, and I'm sure it takes 4000 ppm. Sent it back to John at Speartech and he went back and checked everything (trying to find a copy of HP Tuners now so i can dive into this more).
I may just break down and buy a new IAC, (AGAIN) to make sure that isn't it. I hate problems like this. oh and pics will be up shortly. Still got some tidying up to do and I can't find my digital cam lol
the pic of my speedo is with me doing approx 70 mph.
I currently have a 95 Camaro Z28 cluster in my car, and I'm sure it takes 4000 ppm. Sent it back to John at Speartech and he went back and checked everything (trying to find a copy of HP Tuners now so i can dive into this more).
I may just break down and buy a new IAC, (AGAIN) to make sure that isn't it. I hate problems like this. oh and pics will be up shortly. Still got some tidying up to do and I can't find my digital cam lol
the pic of my speedo is with me doing approx 70 mph.
Last edited by GA95DCMSS; Sep 17, 2008 at 03:10 PM. Reason: Added pics
Joined: Nov 2001
Posts: 1,707
Likes: 33
From: Anderson, Indiana
Start the engine, and when it sounds like it's at about the right idle speed, unplug the IAC connector. If it stays idling correctly and stops climbing, it points to a wiring problem, not a bad IAC or vacuum leak.
Try that and report what happens.
Try that and report what happens.
__________________
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
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Tried what you mentioned John, and it kept climbing. I can unplug the IAC and start the car and it will still climb. Could a major exhaust leak or bad O2's cause this? I had a GM Tech2 hooked up to it and at one point I was getting bank 1 and bank 2 lean codes, and of course, high idle codes.
Could it being programmed for A/C and not having it cause this?
Could it being programmed for A/C and not having it cause this?
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I think you have intake manifold sealing problems...especially with those codes, and a skyrocketing idle as the temp comes up. Have you tried spraying propane around the edges of the intake manifold where it meets the heads while the car is trying to idle? If you do that and the idle races higher while you're doing it, then you need to remove the intake and figure out why it isn't sealed properly...LOTS of people overtorque the intakes on these engines...and since you have an LQ4 with either an LS1 or LS6 intake (I can't tell from the pic) then it's possible that whoever installed it did overtorque it...should be an easy fix too though...and it could be that when the engine is colder it seals a bit better than when it warms up...or maybe it's idling low (and real lean...on the verge of stalling) in open loop and then when it hits closed loop the O2 sensors try to add fuel, which makes it stronger...thus the higher idle...and also the bank 1 and bank 2 lean codes.
I don't really have any access to propane out here lol so I'll have to try and find a substitute. What else can I use? Well I saw that my exhaust clamps were loose, and I was talking to the guy that put in my O2s and he said something about dropping one in a pan of tranny fluid!!! Would that kill an O2 sensor?
On The Tree
Joined: Jan 2007
Posts: 116
Likes: 0
From: Florida
Are you getting any trouble codes besides lean and high idle? Any oil on an O2 sensor will kill it, Rock Auto sells them cheap half as much as dealer. Exhaust leak will have an effect on your problem if leak is before O2's or is within 18" or so after O2's. Good luck, electrical greminlins are the worse.
Besides Bank 1 and 2 lean and High idle...no such luck. I got some O2 sensors waiting for me at the post office right now so all I gotta do is pick them up and plug em in. The leak is within 6 inches of the O2s. I'm running Street and Performance headers and my mid-pipes aren't sealing all that great.
go get some carb clean and mist methodiclly around the intake sealing area. dont go spray happy. pay attention to your idle when doing this. idle should drop and the engine might even shut down if there is a big enough vacc leak. have you hooked up a vacc gauge to check vaccum? do the above mentioned before throwing parts at it. oil will kill 02 but your idle should not be affected, engine should still run perfect cause it will be running in open loop, it will be running rich though.
Would brake clean work too? I have a can of that in my car. I pulled the intake manifold off the car last night and checked under it and checked the sealing surfaces for the gaskets, and everything was good. I'm going to put it back on today and see what it does.
Alright, Got a question. I converted my O2 sensors from the truck O2s to F-Body O2s. I've looked at schematics to see if its wired right, but I'm not 100% sure it is. Any one have any input on how they should be wired?
On The Tree
Joined: Jan 2007
Posts: 116
Likes: 0
From: Florida
2 wires are for the heater (pink & black) Tan is the low signal wire and purple is the high signal wire. My O2 conector is wired A-tan, B-purple, C-black, D-pink. Does your O2 eng harness have the female connector or male connector? Why did you rewire for the F-body O2's.
2 wires are for the heater (pink & black) Tan is the low signal wire and purple is the high signal wire. My O2 conector is wired A-tan, B-purple, C-black, D-pink. Does your O2 eng harness have the female connector or male connector? Why did you rewire for the F-body O2's.
TECH Fanatic
Joined: Jan 2007
Posts: 1,029
Likes: 0
From: LITH, IL.
Looks like you swapped a Z28 cluster in there. As I recall, the 94/95 Impala's are using a half speed signal for the speedo vs the Z28 and 96 Impala. Not sure if you can fix it with programming or if you need to make a signal converter
The Z28 cluster was workng fine with the LT1/4L60E combo. Does anyone know what the VSS output is for the LS1 4L60E? I'm pretty sure it is 4k PPM just as it was with the LT1 4L60E.