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TPI ***Update***

Hossbaby50

Hossbaby50

3/4 ton status
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Location
Peoria, AZ
I got my TPI running yesterday as you may have read. Now I am trying to tune it and get it running well. I am having a problem with my idle. Once the motor runs for a little while (1-2 minutes) the idle gets real erratic. It dips, picks up, dips picks up, etc. The more it runs the worse the idle gets. It will eventually stall out.

I reset the TPS. It was at .570 volts and I set it to .508 volts.

My 0xygen sensor is not installed right now. Would this do it or contribute?

Also though if I rev the motor up (say 3K) and hold the throttle there the RPM will stay for a few seconds then drop down (2K) and pop up some and drop again, etc.

I am thinking my TPS might be bad but I don't know.

No codes are set though. (beside 12) and the check engine light doesn't appear while the motor is on. Thanks

Harley

*******************
Update:

I had the 02 sensor bung installed today with my new cat and everything seems to work correctly now. I have a little idle tweaking to do but it is running pretty damn well. I am a happy camper. /forums/images/graemlins/thumb.gif
 
Re: TPI Idle Question

Harley,

Don't forget about the Idle Control Motor, make sure it's working and clean, may need to reset it alos. Alos don't forget that the O2 sensor does have a lot to do with this, the ECM is looking for a signal from the O2 to adjust the setting and mixture.

Also, the idle is also controled by the ECM, the first 5 to 10 minutes of running is a learn mode, it sends the setting to the block learn mode in the ecm. The idle setting is controled by the burn of the chip. Factory setting is 600 rmp at 8degrees btdc. What type of chip are you running??

Reset :idle air control motor, TPS
Check :timing and ecm setting for chip program, need computer & software.
Install: O2 sensor.

Rob
 
Re: TPI Idle Question

[ QUOTE ]
I got my TPI running yesterday as you may have read. Now I am trying to tune it and get it running well. I am having a problem with my idle. Once the motor runs for a little while (1-2 minutes) the idle gets real erratic. It dips, picks up, dips picks up, etc. The more it runs the worse the idle gets. It will eventually stall out.

I reset the TPS. It was at .570 volts and I set it to .508 volts.

My 0xygen sensor is not installed right now. Would this do it or contribute?

Also though if I rev the motor up (say 3K) and hold the throttle there the RPM will stay for a few seconds then drop down (2K) and pop up some and drop again, etc.

I am thinking my TPS might be bad but I don't know.

No codes are set though. (beside 12) and the check engine light doesn't appear while the motor is on. Thanks

Harley

P.S. disconnecting the MAF seems to help a little bit to even out the idle but doens't fix the problem.

[/ QUOTE ]

No O2 sensor hooked up? How is it NOT setting a code? The TPS should be set at .54 +/-.075 by the way.

Sounds like you need to reset the IAC for starters - here's how.......

IAC and TPS adjustment

Then check for a vacuum leak.......... /forums/images/graemlins/laugh.gif
 
Re: TPI Idle Question

Can't recall if you mentioned it or not, but is VSS hooked up?

With O2 disconnected first off, you shouldn't be going closed loop. Should be codes as mentioned. Without closed loop, I'm not sure if any "learning" is done with the ECM.

If VSS is not hooked up, IAC will be screwed up once the ECM loses power. The ECM uses VSS to "calibrate" the IAC, so without VSS input, it can't "set" the IAC to where it needs to be.

However, without O2, you shouldn't be going closed loop, which shouldn't make any difference for idle, since that is pre-programmed. With engine mods and no PROM mods, this might be an issue as well, but only noticeable if the engine is a fair amount different than that originally used with the ECM you have.

BTW, for others that have done the swap, anyone used the "choke" light in the cluster as the check engine lamp? If you find an 87-91 truck, the overlay is "check engine" (or SES, whatever) and replaces the choke overlay exactly. I plan on doing this with my truck, but not sure how the printed circuit wiring of the two compares. Figture this may help you too Harley, if you don't have a check engine light.
 
Re: TPI Idle Question

The O2 sensor is hooked up but not installed in the pipe yet. It is just laying in the engine bay. It is a heated 02 sensor.

I have no VSS hooked up yet. I am going to order the VSS sensor tomorrow.

I do have a check engine light that is mounted on my ALDL line. It works. If I have the MAF or TPS disconnected it will light up. With everything hooked up it doesn't light when the motor is running and doesn't throw any codes.
 
Re: TPI Idle Question

With no VSS, I'd say that is at least one of your problems. This is well documented as one of the main reasons VSS is necessary for good driveability with TPI or TBI. You can search over at thirdgen.org for VSS and IAC and I'm sure you'll see the same there.

Heated O2 or not, without the proper voltage generated from exposure to exhaust gas, the system is going to be screwed. Probably attempts to go closed loop and isn't getting the response it expects and should see. It is basically a rich/lean sensor, outside of the exhaust stream, it will read lean, which means pulse the injectors longer.
 
Re: TPI Idle Question

I am taking it to the exhaust shop tomorrow to have the 02 sensor put in along with my other cat converter. I am going to order the VSS off Jegs right now so I will be able to get that squared away too. I have to use it so that the EGR valve will work since I live in an emission county and have to pass emissions this month.

I found that one of my vacuum ports wasn't blocked off so I put a cap on it and it helped out alot.

My other problem right now (I just got back from a short drive) is that I am not getting the throttle response and low & mid range power I should be. I only get power when I punch it. I will see what the 02 sensor and will try and tune the IAC and TPS tomorrow too.

Harley
 
Re: TPI Idle Question

I seem to remember on my '91 TBI that if you disturb the TPS you need to drive at a certain speed or above (think it was 30mph) for a short time for the TPS to set itself so it knows what it's doing in relation to the other sensors.....Bl***y computers!!!
 
Re: TPI Idle Question

[ QUOTE ]
I am taking it to the exhaust shop tomorrow to have the 02 sensor put in along with my other cat converter. I am going to order the VSS off Jegs right now so I will be able to get that squared away too. I have to use it so that the EGR valve will work since I live in an emission county and have to pass emissions this month.

I found that one of my vacuum ports wasn't blocked off so I put a cap on it and it helped out alot.

My other problem right now (I just got back from a short drive) is that I am not getting the throttle response and low & mid range power I should be. I only get power when I punch it. I will see what the 02 sensor and will try and tune the IAC and TPS tomorrow too.

Harley

[/ QUOTE ]

After you get the O2 sensor working properly (in the exhaust stream) let us know if that helps your issues. Re-set the TPS to .57 or so. Mine liked to be set at .60, if I remember right you're at .54 volts.

Also, all due respect to Dorian, not running VSS is not the end of the world. I had mine set up like that for over 2 years and honestly had NO problems, only reason I hooked it up was to see if all the crap I was getting for not having it hooked up was true. I had NO idle problems, tho it DID seem to idle slightly smoother but there was NO performance difference. I'd still do it right (hook up VSS) if I had the choice as you do, and are doing. /forums/images/graemlins/laugh.gif

Take my comments for what they are, only MY real world experience. /forums/images/graemlins/laugh.gif
 
Re: TPI Idle Question

[ QUOTE ]
Take my comments for what they are, only MY real world experience.

[/ QUOTE ]

No offence taken. I think just like everything else, results vary.

I don't think VSS is what is harming your actual performance, just the VSS is important to proper IAC operation.

I just know what others have experienced on thirdgen.org with VSS/poor idle issues, which is what I was commenting on. I know there were a few there that were adamant that VSS wasn't necessary, and had very little effect even on idle, and I'm sre at least some of them were speaking on the basis of personal experience as well.

FWIW there are at least 3 IAC pintle designs (on '88 camaro alone) so that could also have something to do with the varying results.
 
Re: TPI Idle Question

My TPS is set at .508. I read in the manual that it should be at .50 so I got as close as I could.

*reset TPS to .55 earlier tonight*

*timing is 7* btdc at 700rpm (roughly)*

I ordered my VSS last night. It should be here Friday or Monday.

Thanks
Harley
 
Update:

I had the 02 sensor bung installed today with my new cat and everything seems to work correctly now. I have a little idle tweaking to do but it is running pretty damn well. I am a happy camper. /forums/images/graemlins/thumb.gif

FI is sweet. You can go out to the truck hit the key and vroom. No pump the gas, no nothing. Not to mention that it runs alot better then it did with the carb, even when the carb was running well. The coolest part is when you really stomp on the loud pedal you kickdown and take the hell off. I can say this swap was totally worth the time and effort to do. Took awhile and some cash but it was worth it on so many levels. It runs alot better, better performance, and it looks really cool too. /forums/images/graemlins/thumb.gif

Harley
 
Your making me jealous..... Did you do a right up with pic's....
 
Another Update *** I didn't pass emissions today but it wasn't because of the TPI. I have to reroute some charcoal canister lines and block off a fuel line. I failed the tank pressure test and the emission hose routing. The actual tailpipe emissions passed very easily. ***

No, but I might be able too. I don't know if I am the right person to do it though. I did it, but I had alot of help and advice from people that know much more about it then me. I am sure I would have alot easier time doing it again now that I have done it, but right now I don't have all the knowledge and stuff that alot of others have.

I could do a basic hear is what you need to do and install article but I would need to borrow someones digital camera.

Harley
 
>>>>>>>>>>>>>>Mine>>>>>Pass
Hydrocarbons: 0.63>>>>>4.40
Carbon Mono: 13.48>>>>48.00
O2 of Nitrogen: 2.67>>>>7.00

These are all grams per mile.

All keep in mind that I don't have a Vehicle Speed Sensor installed yet so I don't have a functioning EGR valve. So this is straight motor with cats and air pump. No EGR

Harley
 
Hard to relate that to CA #'s because they use parts per million here. Nice to see you made it by such a large margin.

If the goal is truely reduced emissions I see no reason for the underhood inspection. If it passes without EGR let it run!
 
Because it passed so easily without the EGR in operation I think I am going to install my VSS so I can have my computer control my 700R4 but I am going to have my computer sent out and have the EGR programed out of the chip so it won't be used and I can just block off the EGR passage in the manifold. It is not like they can see the EGR valve on a TPI motor anyway. It is buried under the intake runners and plenum.

Harley
 
Sounds like a good idea to me /forums/images/graemlins/thumb.gif

I never thought putting exhaust back into the intake was a good idea.
 
Come summer time you'll be wondering why the engine feels a little weak. /forums/images/graemlins/shocked.gif The timing curve is pretty agressive, even with a stock TPI chip. Add in some hot intake air (like those "mild" Phoenix summers) and the engine is gonna start pinging. But you'll probably never hear it. The knock sensor will detect it and pull timing out of the ignition to stop the pinging, resulting in less power.

Lots of people think that any emission control should be removed in search of power. But EGR is actually a good thing, especially at part throttle under heavy loads. It turns off at wide-open-throttle, so it doesn't affect hard acceleration. /forums/images/graemlins/thumb.gif
 
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