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excessive high idle

BenDiesel

BenDiesel

NAXJA Forum User
Location
lynnwood washington
ok i got a 89 4.0 auto with a 91+ apm header and a 99+ intake i am running the factory 89 injectors, and adapted a renix tps to work with the 91 tb

so when i start it up it revs up to 2000rpm. when i put it into gear it drops to about 1k . i know i need to adjust the tps, i know it on the low side of the volts,but could that cause the problem?

i know the earlier model of the renix were learning computers, is the 89 one to? can it compensate for the removable of the egr system?
 
Well, IAC affects idle speed.. I would start with that.
Renix computer has no memory, so when you shut it off that's that.
Pull it, check it for damage, clean it and your TB with TB cleaner (not carb cleaner). And re-install it and check it.
 
I had a similar problem and it was a vacuum leak. start with the cheapest easiest first :)
 
cruiser54 said:
You need to get that TPS adjusted first. Otherwise you're chasing your tail. Then check for vacuum leaks.
Click to expand...

Agree.

If the TPS is out of whack, it is TELLING the ECU something that isn't true, and the ECU is extending/retracting the IAC based on false data.

All Renix ECUs are real time.
 
I'm still fighting with idle issues as well. I'm going to try adjusting the TPS tonight. On Lunghd I found the adjustment instructions, it says to set the TPS to 4.2v for the automatic transmission, will this be the same voltage for a 5 speed?
 
MudfrogK5 said:
I'm still fighting with idle issues as well. I'm going to try adjusting the TPS tonight. On Lunghd I found the adjustment instructions, it says to set the TPS to 4.2v for the automatic transmission, will this be the same voltage for a 5 speed?
Click to expand...

no, the output voltage should be 17% of the input voltage.

if the input voltage is 5volts, then the output should be .85volts

.85/5=.17 or 17%

this is opposite of the auto trans which is .83 or 83%

4.15/5=.83 or 83%
 
Are you using the renix head? Maybe the intake ports don't line up exactly with the intake manifold. I know that my renix intake does not line exactly with the HO head I have, so I had to notch the alignment holes to move the intake in a better location and do a little porting to match with the intake runners. I would consider using a HO head, as you will gain a little more power.
 
ya i noticed i had 2 vac leaks. now its down to 1k at warm idle not in gear. but a new problem has aroused. it starts and runs fer a sec and dies its low on fuel bit still reads 1/8 tank. but who knows if that acurate

as fer adj the tps i seen so many that say differnt things. which plug goes to the trans and which to the engine? why do some sat adj to .80 volts and others to 80% i am so confused
 
Based on the post above if you have the auto trans you need to adjust your TPS to .83 of the voltage.

I have a 5 speed so mine was .17

My voltage read 4.49 so I adjusted my TPS to .76 which is 4.49 * .17 (I rounded).
 
Ben, put it in gear, it's supposed to be ~750rpm in gear warm idle.
 
ok i went to adjust the tps today.i measured the input volt at 4.63
so check my math
4.63 x .8= 3.70

so i tried to adjust it down. the lowest i could get it was 4.07 looks like i need to make a shim to space it down more. but i may leave it there cause it starts easy and idles perfect
 
BenDiesel said:
ok i went to adjust the tps today.i measured the input volt at 4.63
so check my math
4.63 x .8= 3.70

so i tried to adjust it down. the lowest i could get it was 4.07 looks like i need to make a shim to space it down more. but i may leave it there cause it starts easy and idles perfect
Click to expand...

I would. Just remember if you have any shifting issues down the road you may need to revisit the TPS.
 
koo thanks for the reply. what should i look for in problems? lol this is my first computer controlled vehicle. every thing else i had was hydraulic auto or manual and all with carbs lol
 
BenDiesel said:
ok i went to adjust the tps today.i measured the input volt at 4.63
so check my math
4.63 x .8= 3.70

so i tried to adjust it down. the lowest i could get it was 4.07 looks like i need to make a shim to space it down more. but i may leave it there cause it starts easy and idles perfect
Click to expand...

your math is wrong, you divide, not multiply

output/input .80/4.63= .17(100)= 17%
not
output X input
 
89xj said:
your math is wrong, you divide, not multiply

output/input .80/4.63= .17(100)= 17%
not
output X input
Click to expand...

89xj is right--if you have a manual transmission.

BenDiesel: Auto or manual transmission?

Manual transmission TPS: output voltage should be 17 percent (.17) of reference (input) voltage. Example: reference is 5.0 volts, you want output to be .85 volts; reference is 4.5 volts, you want output to be .765 volts--round as appropriate for your meter.

Automatic transmission TPS: output voltage should be 83 percent (.83) of reference (input) voltage. Example: reference is 5.0 volts, you want output to be 4.15 volts; reference is 4.5 volts, you want output to be 3.735--round as appropriate for your meter.
 
Shortly after I installed my APN, I developed an extremely high idle.

Check your intake and make sure it's good and tight. A couple of my bolts had backed off.
 
HaleYes said:
Shortly after I installed my APN, I developed an extremely high idle.

Check your intake and make sure it's good and tight. A couple of my bolts had backed off.
Click to expand...

Or the intake will sometimes "hang up" on the locater pins--make certain it is fully seated on them.
 
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