Hey Guys,

A couple years ago we had our 105K miles suburban in for an engine rebuild due to the oil blow-by caused by bad rings and the cylinder management. Anyway, after the rebuild we had an intermittent DTC for the Throttle Position Sensor 1. The check engine light is now on all the time. I've noticed that when returning to idle after driving (i.e. pulling into my garage) the car tends to surge a bit. So I'm pretty sure the TPS is bad.

It's my understanding that on this model the sensor cannot be removed and you have to replace the Throttle Body.

Before I order this part I'd like to get some feedback on some things I can try to maybe fix the issue.

If I do need to replace the throttle body, is there maybe a better throttle body than OEM that I can get that might improve MPG? Would TB spacers be worthwhile?


Thanks!

 

Welcome to the forum

What codes are you getting specifically ?
I have always been under the impression the throttle body was replaced as a unit, but I have heard others say they can get just the sensor unit.. but given the miles you have replacing the whole unit might not be so bad as the throttle assembly can wear over time...
As for spacers, fancy CAI and filters and the like, if they really worked the auto manufactures would have already installed them if they could claim more MPG.. (your stock intake is a CAI system, that has baffles installed to muffle the engine sucking in air, aftermarket CAI, remove the baffles so you hear the engine breathing but nothing has really changed except what you hear, sounds cool as shick though!)

You can get a ECM tune that can tweak your engine for slightly better MPG but to gain MPG, you have to take way from response and power and vice versa if you want power and response you're going to loss some MPG...
Given the miles you have, you're not likely to find any miracle cures to bring it back to anything better then what you have had in the past...

I always recommend OEM parts, they are parts that have lasted you this long, and if you find something less expensive its likely because its made that way i.e. less expensive ( read cheap) ....

 

Hey, thanks for the response.

And let me start by saying that I've done a little research and if anyone has thrown and/or broken anything after reading me ask about TB spacers - I offer to repair/replace those things at no cost to you.

I removed the air intake resonator on my '03 Acura TL and now she purrs under load and growls like an R35 at WOT. I think I'll do the same for my suburban. But I hear too many conflicting anecdotes about resonator removal - either you lose 2-3 whp or lose 0 whp. I'm not sure what to believe.

I don't remember the exact code and I don't have it in front of me. However at the time I looked it up and 100% of the time it was recommended to replace the throttle position sensor. The only trouble is that in this model year, inexplicably the sensor is riveted into the TB. I've heard of people drilling out the rivets on the old sensor and replacing with a new one, but the trouble is, what do I replace it with? I can't find a TB sensor by itself for an '07 - only a TB assembly.

 

I have this intermittent DTC as well. Funny thing is, it seems to always happen in the same or similar areas. So not sure if its from length of time driving, or vehicle angle or something, but it does stay gone for awhile after I clear the code.

I was going to try cleaning it, but I don't know if it would make it worse, or if I want to deal with re-learning the throttle body thing. Did it on my wifes envoy and it seemed to help but took quite awhile to get the computer to relearn everything.

Anyone think cleaning is worth looking into? For the record, it doesn't seem to act any different before during or after, just the annoying light is on.

 

Cleaning it is an easy no cost* place to start, worst case it doesn't resolve the issue.... city driving with lots of stop and go seems to be the best way to self learn the TB, or you can pay the $100 bucks to have the learn procedure done at the dealership....

 

Thanks. I'll probably just do it to start and see what happens. Not like I haven't done it before. Since I am the main driver I can deal with it the relearn.

When I did the envoy, I wouldn't let my wife drive it...cause it was still learning...and idling high. Felt like it would just take off on you sometimes. After a bit of messing around disconnecting the battery and letting it sit, and a healthy dose of stop and go, it finally corrected itself.

I just have to remember not to take on too many projects at once. Usually I do to much at once then when I run into issues, I'm not sure where to look at first. With the envoy it was air filter/trans cooler/thermostat (which also ended up adding itself into a temp sensor)/TB cleaning. Then I had the relearn which I hadn't expected.

Step at a time this time I think.

 

My wife was driving out 2007 Tahoe LTZ to church last night and I get a call from her after she just left the house, and she said the car wont accelerate past 30 mph or so. I told here to come back home, I let her take my 2014 Jeep Grand Cherokee (which I hesitated to do, b/c its my baby and I don't like the way my wife has treated this Tahoe, lol). So she had to go gas it up, while she just left again, I started the Tahoe back up, the CEL was still on but it ran fine, I caught up to her at the gas station and just let her drive the Tahoe instead, lol. So I get up this morning to get the CEL scanned, and I start the Tahoe, no CEL anymore. I went to go drive it anyway to see if they could scan it (at AutoZone) for stored codes. As soon as I turned the 2nd corner out of my neighborhood, warning chime came on, CEL came on, Traction control light and message came on, service stabilitrak message came on, engine power reduced message came on and it wouldn't accelerate well. Came back home, had to pay almost 150 bux to borrow a OBD 2 scanner from AutoZone, but I get my money back if I return it in working order. Came home and scanned the Tahoe, got a P2138 "Throttle/Pedal position sensor switch "D"/"E" voltage correlation CONFIRMED". The 2nd code read was also P2138, but had the same verbage except for the last word was PENDING.

I can't remember the other I had gotten when the TB was gummed up and I had cleaned it out. And BTW, it took my Tahoe a long while to relearn after the cleaning, somewhere like 600-800 miles, which I thought was a bit long. But I don't remember it reducing engine power, all it did was turn on the CEL and that was it. I'll have to research this code more, since it looks like I have the same issue as the OP, I may clean the TB first and see what happens, if it goes away great, if not I'll just buy a new TB.

UPDATE: after more research I feel that that the P2138 is referring to the accelerator pedal. So I disconnected it and blew compressed air thru all the connectors (I have a sprint booster module) and cleared the code. All seems fine for now. I will monitor and update.

 

Given all the electronics and electrical connections in vehicles now days, the simple act of disconnecting, cleaning and reconnecting connections can solve ALOT of issues.... and is always a good place to start, the issue might come back and the part need to be replaced, but more often then not its simply oxidation or poor connection due to vibration....
Blowing them out is okay but a shot of contact cleaner or simply using IPA (alcohol) that you might have under the bathroom sink that is at least 50% (higher is better as it evaporates more quickly) will also do the trick for cleaning up the connections...

Also when using a meter to probe the connections for voltage be careful not to force the probe tip into a connection and open it up so much that it will no longer make good contact with its mating pin... this is always a big gotcha that leads to more problems

 

Thanks for the suggestion! Just a quick update, all has been well since my last post.