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Mid-range surging?


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13 replies to this topic

#1 soobme

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Posted 23 October 2005 - 04:29 PM

I just got my 1st 3dr, and it's my 1st SPFI car. It has a strange problem, it suges @ mid throtle. About 1/3 through 2/3 of the gas pedal it's like I'm fethering the gas a little (some times a lot). It dose not seem to be RPM dependant, just pedal possition dependant.
Would this be a TPS? Is there a common cause of this condtion?


#2 Snowman

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Posted 23 October 2005 - 04:59 PM

I have been told that the TPS likes to wear out/get dirty over time on these cars, causing the exact condition you describe. My SPFI conversion did the same thing for a while but it eventually became not as bad...the sensor was probably dirty from sitting for a couple of years (and being from a car with 205k on it).

#3 soobme

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Posted 23 October 2005 - 05:13 PM

That's what I would think it is just from the way it acts. I figure it never hurts to ask thoe.
Any one know if I can take it apart and clean it? Or do I just need to get a new one?


#4 hooziewhatsit

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Posted 23 October 2005 - 06:13 PM

I just got one from the junkyard to hopefully get rid of my surging while cold and driving slow.

It doesn't appear easy to take apart and remove. Best bet is probably to get a used one from a junkyard. I think they're very expensive new.

There's a link in here to a method to test it.
http://www.ultimates...position sensor

#5 tizzle

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Posted 23 October 2005 - 07:02 PM

Yep, ridiculously expensive new. I think Napa said it was a couple hundred. What's the deal with that? Its not a complex device.

#6 bulwnkl

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Posted 23 October 2005 - 07:20 PM

Have you put a meter on it to see whether the resistance/output is stable or variable? I have had a similar condition on my XT6 for a while. A couple of us on XT6.net describe it as "power waves." A new (used) TPS had no impact. A new coil seemed to help some, but it's not gone.

I'd love to know if you resolve it this way, because I have been totally unable to find or eliminate this problem.

#7 soobme

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Posted 24 October 2005 - 12:42 AM

No, I have not tested yet, but I will in the morning. If I get any out of whack readings I will get one @ the yard ASAP. If that isn't the cure I'll try a new coil. I will post back as soon as I have cured it;)
Thanks for the link to the other thred! That info.&PDF file will be VERY handy:clap:


#8 hooziewhatsit

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Posted 24 October 2005 - 02:05 PM

just an FYI...

it appears that to change the TPS, the AC compressor (if you have one) needs to be unbolted and moved about 1/4" tops :banghead: I'm thinking about maybe grinding down on the AC bracket to make the room, :rolleyes:

If anyone has any tricks to removing/replacing these things, please let them be known :-)

#9 tizzle

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Posted 24 October 2005 - 03:06 PM

I have one of those flexibe/bendy screwdrivers, which worked great. I didn't have to move anything. Putting tps back on is a little bit of a pain.

#10 hooziewhatsit

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Posted 24 October 2005 - 03:49 PM

I just got mine swapped out...

found a LONG flathead screwdriver, and was able to loosen both after removing the vacuum line to the brake booster.

To remove the TPS, I had to file down on the AC compressor with a 10" file I have.

The wire bundle running through there I had to pull up on top of the compressor to get out of the way. After filing quite a bit on the compressor I was able to slide the TPS off. A little more filing for kicks & giggles and now it goes on/off just fine. Much easier than moving the alt/compressor/fan shroud/etc to get some space to work in.

At the moment I only have the top screw holding it in place until I get a final driving test/adjustment.

#11 soobme

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Posted 25 October 2005 - 04:05 AM

I did not get a chance to test it today, but after reading this I'm glad I don't have AC:-p I'm wondering if there is a Nissan TPS that would work on our Roos that could be had for cheeper. I know that some of the other Nissan FI parts can interchange:brow:

#12 hooziewhatsit

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Posted 25 October 2005 - 09:54 AM

:banana: NO MORE low speed surging while cold :banana:

#13 soobme

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Posted 25 October 2005 - 12:00 PM

COOOOOOOLLLLLL!!!!!! Hopefully that's all that is wrong with mine too.

#14 azsubaru

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Posted 25 October 2005 - 06:52 PM

A new TPS fixed the same problem for me, too. I took the old one apart to see if they're fixable. The bottom line is that I don't think you could really fix a worn TPS, but if you have an idle switch problem you might be able to clean the contacts with a burnishing tool. If I ever get a good camera I'll post pictures.

You could try blowing some electronic cleaner into it just in case it's dirty and not worn.




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