Ed Maher

After the recent spat over stickies, i came up with this as a possible compromise for everybody. Welcome to the FAQ building post, or an index for common stuff. What i'd like to see this used as is a simple place to put a link to a thread with a short explanation if you found it particularly helpful.

Now the rules. Keep things as brief as possible. I'm going to put a few things in the next post as an example of what to do. Also, i reserve the right to prune and edit this whole post as necessary. For example, combining threads into one if they all are on a common topic, like common first mods would be best kept in one thread, etc. Oh yeah, please don't use sigs, or otherwise interject pictures or anything either or i will just edit it out. This is probably going to be a huge thread in time, and i want it to stay as simple and data-small as possible.

What's the point. Well, if you want to write a FAQ / Tech article type post on something, you can, and then link it here so it doesn't get lost. And the board itself gets to stay clean and not be cluttered with stickies, while still making it easy to find all the best stuff.

Ed Maher

Holley Stealth Ram FAQ -
https://www.thirdgen.org/techbb2/sho...hreadid=114308
https://www.thirdgen.org/techbb2/sho...38#post1183338

LT1 intake FAQ -
https://www.thirdgen.org/techbb2/sho...hreadid=146874

Siamesed Base TPI -
https://www.thirdgen.org/techbb2/sho...antituning+TPI
https://www.thirdgen.org/techbb2/sho...antituning+TPI

Ed Maher

Porting the Plenum (Vader's article) -
http://72.19.213.157/files/PlenumPorting.pdf

Air Foil (one of a million with the same message) -
https://www.thirdgen.org/techbb2/sho...hlight=airfoil

Throttle Body Coolant Bypass -
https://www.thirdgen.org/newdesign/t...ntbypass.shtml

A.I.R pump bypass, also shows PS bypass -
https://www.thirdgen.org/newdesign/t...rpentine.shtml

TPS and IAC adjustment -
https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

Injector Swap -
https://www.thirdgen.org/newdesign/t...ctorswap.shtml

Edited IP for links - Vader

Ed Maher

Why exhaust backpressure is bad -
https://www.thirdgen.org/techbb2/sho...t=backpressure

Ed Maher

Fuel Rail and injector GM part numbers (good for reference) -
https://www.thirdgen.org/techbb2/sho...ail+blue+oring

Injector Cleaning and Flow Matching Service -
www.cruzinperformance.com

Bort62

7749 ECM conversion -
http://www.speedtoys.com/~bort62/7749/Main.htm

Bort62

Reasons why they are a waste of money -
https://www.thirdgen.org/techbb2/sho...hreadid=104116

Ed Maher

General Tip - this will give you a sorted list of the most viewed topics all time. Happened to sort on it for kicks and seemed like it brings up a lot of good posts You could do the same for replies and probably get soemthing close

https://www.thirdgen.org/techbb2/for...=1000&x=10&y=7

And oh yeah. You don't have to ask for permission to add something if you think it's a good idea. One last thing. You don't necessarily have to ressurect old topics, especially if what you're adding isn't especially germane to the conversation.

89 Iroc Z

Build Your Own Adjustable Fuel Pressure Regulator:

http://members.aol.com/mmmm999/3rd-d.../afpr/afpr.htm

89 Iroc Z

Buffing the Plenum:

http://www.gmtips.com/3rd-degree/dox...m/pol-plen.htm

89 Iroc Z

Another Plenum Porting Artical:

http://www.gmtips.com/3rd-degree/dox...-port/port.htm

8Mike9

1. Post your engine spec's
2. Retrieve any stored codes. Look at the main page in Tech Central for the How To

Ed Maher

Pictures / Description of what needs to be done to put a 58mm TB on a stock plenum
https://www.thirdgen.org/techbb2/sho...highlight=58mm

AMRformula305

TPI

How O2 sensor affects new AFPR.
https://www.thirdgen.org/techbb2/sho...hreadid=253801

Zap Racing

Vader's article on Tps and Iac adjustment:

Moderator, if U know a better way to archive this here than reprinting the article, please do so!



Yes, the engine should idle at the specified RPM for minimum air position adjustment (in DRIVE with an automatic).

I'm not sure what article you may have read, but try this procedure:

Throttle Minimum Air Position

Tools needed:
1. Torx driver # T-20
2. Paper Clip
3. Small Punch
4. Tachometer

GENERAL NOTE: The engine should be at normal operating temperature before performing any adjustments. Never rely on the dash mounted instruments for diagnostics and adjustments. The oil pressure and temperature gauges and the voltmeter and tachometer just aren't calibrated accurately enough for diagnosis, but are a relative indication for monitoring the vehicle while driving.

For this adjustment, the transmission will be in DRIVE while you're under the hood. You will need to securely set the parking brake and block the drive wheels. It would also be a good idea to have an assistant hold the service brake while you perform the adjustments.

In order to successfully complete the adjustment, the IAC air passages and pintle need to be clean. The throttle plates and bores need to be clean as well. If this is not the case, you'll need to remove the air cleaner from TBI engines or the intake air bellows from TPI engines to gain access to the area to be cleaned. A spray-type carburetor cleaner works well for this. Cleaning the IAC passages on a TPI/MAF engine will set a DTC, but we'll be clearing that later. With the engine idling, direct the spray cleaner in to the IAC air passages and around the throttle plates. Shut off the engine and continue cleaning the throttle plates by opening the throttle manually. Once everything is satisfactorily cleaned, replace the air bellows on TPI engines. Many times, this alone can solve IAC/idle speed problems.

If this doesn't solve the problem, you may need to remove and clean the IAC stepper motor. If the IAC appears to be clean and functioning properly, continue with the adjustment procedure.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Idle Air Control Cleaning

You can remove the IAC and service it. Remove the electrical connector from the IAC. Unscrew the IAC unit from the throttle body.

You can gently rock the pintle back and forth and allow the spring to extend it until it comes apart in your hands. Clean everything with lint-free cloths and a mild solvent. Harsh solvents can affect the insulation of the stepper motor coils. It's generally the dirt and buildup on this worm shaft that causes sluggish IAC operation.

When the worm gear on the pintle shaft is clean and dry, apply one drop of clean light oil to the shaft and work the pintle back into the rack gears of the motor by the same rocking motion. It takes a while to get the pintle back into the worm gears, but you'll get it. It is important to get the pintle fully retracted into the housing so that the pintle is not forced against the gears when reinstalling the IAC unit in the throttle body.

While the IAC is out, clean the air passages in the throttle body. The orifice in the TB where the IAC resides is the seat that the IAC valve closes against, and it can accumulate a lot of carbon, dirt, and debris. The easy way to do this is with carburetor cleaner and a small stiff brush.

When everything is clean and dry, replace the gasket if it is damaged, apply a little anti-seize to the threads, and torque the IAC to the proper specs. (13 ft/lb for '85-'89 , 30 in/lb for 1990-on.) Proceed with setting the TPS and minimum air position.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Locate the ALDL connector under your dash panel, in the driver's footwell area. Remove the plastic trim cover (if it is still there).



Cut and form a paper clip into a "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' sockets.



Turn on the ignition, but don't start the engine. This will force the ECM into its diagnostic mode. Wait 30 seconds to allow the IAC pintle to fully extend. Under the hood, remove the electrical connector from the IAC, then turn off the ignition and remove the paper clip jumper from the ALDL. With the IAC pintle fully extended (closed) all idle air will be controlled by the position of the throttle plates. Some manuals indicate that the EST bypass connector should be disconnected for this procedure, while some make no mention of it. While timing is a factor in idle speed, the EST should only operate as a function of engine RPM, temperature, and detonation sensor inputs. To remove all doubt, disconnect the EST bypass connector is your car is so equipped. Some TBI and V-6 engines do not have this bypass connector, and therefore must be set with no regard to the EST system. The EST can be bypassed on some cars by grounding the diagnostic terminal at the ALDL and continuing with the procedure, but the fuel mixture will be skewed to the rich side, affecting idle speed as well. In any event, the minimum air position idle speed range is wide enough to allow for some variations. As always, it is best to consult your service manual for the exact procedure for your system.

Locate the Torx screw on the left side of the throttle body. It may be equipped with a protective metal cap from the factory. This was intended to discourage adjustment. If the cap is present, use a small punch to knock it out. Once the screw is accessible, start the engine and place the transmission in DRIVE. Adjust the throttle stop to obtain 400 RPM with the transmission in "DRIVE" on an automatic transmission car, 450 in neutral on a manual transmission car, rotating the Torx screw clockwise to raise speed and counter-clockwise to lower speed. Once the idle RPM is set, place the transmission in PARK and turn off the engine.

Re-connect the electrical connector onto the IAC. Start engine. Idle speed should be governed by the ECM at approximately 600-650 rpm in "DRIVE" (for unmodified cars). Idle speed in NEUTRAL or PARK is less significant, and will be higher.



Throttle Position Sensor (TPS)

Tools needed:
1. Digital Volt-Ohm-Meter (VOM)
2. Breakout jumper wires or probes (make your own)
3. AutoXray, Diacom, or similar scanner will replace the VOM and jumper wires.

Turn on ignition, but don't start the engine.

With a diagnostic scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.07 VDC.

Connect the VOM to the TPS electrical connector terminals ‘A' and ‘B'.

With a breakout jumper: Disconnect the electrical connector from the TPS. Install the breakout in-line, between the TPS and wiring harness connector. Connect the meter probes to terminals 'A' and 'B' on the connector. (‘B' is the positive connection, ‘A' the signal ground, or negative.)

With probes: If you have very slender probes on your VOM, you can back-probe the TPS connector while it is attached to the TPS. If you have made probes of large dressmakers pins or a similar item, you can back-probe the connector as well. Connect the meter probes to terminals 'A' and 'B' on the connector.

Turn on the ignition to read the TPS output voltage at the idle position. The reading should be 0.54VDC +/- 0.07VDC. The ideal is the center of the range, 0.54VDC for a stock engine. To adjust the output voltage, loosen the two Torx screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, the TPS sensor may be failing and could be a cause of stumbling and driveability problems.

After achieving the desired setting, turn off the ignition switch. Remove all jumpers or the scanner and reconnect the TPS connector as required.

Reinitializing the ECM

If you set a DTC during the procedure, the SES light should be illuminated on the dash. This ECM retains DTC data for the previous 50 engine starts, so the codes will eventually be cleared. If you want more immediate results, after shutting down the engine disconnect the negative battery terminal for five minutes. This will clear the ECM of all diagnostic trouble codes. Clearing the ECM also clears any data learned about your engine, and clears the radio presets. If you have a Delco-Loc or Theft Loc II radio, make sure you follow the procedure to unlock the radio protection before disconnecting the battery. This five minutes is also just about long enough to clean both battery cables. Reconnect the battery. When you first start the engine after clearing the ECM, the engine will operate with base parameters programmed into the ECM PROM. These parameters may not be optimum for your engine, but the ECM will enter a Block Learn Mode soon after the engine is warm and enters Closed Loop Mode. The ECM will write new data tables specific to your engine and will eventually rely on those tables instead of the base tables of the factory program. You can expedite this process by driving the car for 20 minutes under varying conditions to allow the ECM to initialize. Or you can wait and drive the car normally at your convenience. The BLM tables are constantly being updated as sensor input ranges change, but the greatest change will occur within the first twenty minutes of Closed Loop operation.

therealmark

http://www.hotrodlane.cc/PDFFILES/TPIStory.pdf

I found this article looking for a solution to my early TPI on late heads problem... I wish I'd found it when I was looking to buy the TPI in the first place. It's a pretty exhaustive look at the years and models of TPI, with lots of pictures to illustrate visual differences.

If this has been or should be posted elsewhere, my apologies... I thought it would be a good addition to the FAQ.

M.

tww316

I am not sure how this works, but I would like your opinion on my injectors in 1989 formula 350. The resistance on the injectors range from 9.8 to 17.2. Five injectors are in the 17 range. One is 9.8 and one is 11.3. All of this is new to me, but you sound like you know your stuff. Can you tell me if these resistance numbers are within the specified range?

Thanks for you help

Rickracer

Ed, check out the way we've done it at http://www.v8s10.org/forum/ , all the good stuff/threads for each forum are linked , in one thread, and any replies get posted to the original thread. Works pretty well and keeps the top of each forum from being clogged up with stickies.

bigE85z28

bad link!!!

abcx09t

Where are the Plenum porting articles and photos? Where is the article on making your own adjustable fuel pressure regulator? The link to Hometown says Hometown is no longer working. Please help.
Scott

38alain

Hi! I have a problem whit the overheating hexaust and eratic idle on my 91 ta gta 5L tpi t5 trans and i have no fautly code . I check for erg valve +coil ,air pompe and coil are good,oxy is good to and i clean the plenum and trottle body??? i need help thanks 38alain

Filthy McNasty

Do you have a Cat.If so sounds like a clogged cat.

38alain

Hi! Some time i heard a SSSSSS at the inlet of the throttle body ?

88PontiacT/A

OK.... Maybe I'm a dumb***, but I don't see aything on the connector that labels a,b etc. So for those of us that are not familiar with this, and that are really tired of searching (but not finding) this information, could someone please divulge the secret to determining which terminals "a" and "b" actually are (actual location on the connector) Sorry I have to ask this. I thought that I saw somewhere a while back that they were the upper and lower far right terminals, but I want to be sure so as not to burn something up. ....
Thanks,
John C.

87IROCZ350TPI

Hey John, I know this is an old post but I'll respond anyway.
Both terminals are on the top row. "A" is far right. "B" is next to "A".
The top row is arranged as follows: F - E - D - C - B - A.
"A" is the ground terminal and "B" is the diagnostic terminal. When you connect the ground and the diagnostic terminals together with a wire or a paperclip, you will initiate the diagnostic mode where you can read any stored trouble codes using the SES light. Just be sure that while the terminals are connected you DO NOT start the engine. You may damage the ECM if the engine is cranked while the terminals are connected. Hope this helps.

lettuce

iTrader: (1)

Wait, you can't start the car with the diagnostic grounded? You can ground with the car running though, right?

rusty vango

according to my 86 FSM, you can start it with the ALDL grounded its called "field service mode"

rusty vango

you can drive the car with the ALDL ports A&B grounded. its called "feild service mode" in my FSM.

kevins88

ive been asking questons on other for help. ive possiblty screwed up my car cause of lack of supervision...installed a lt1 block,with the l98 haeads,intake.etc....now oil is flowing out of water pump,somewhere the water,oil passeges are overlapping.hhhheeeellllppp......

kevins88

you know im gonna speak my mind here....i was attracted to the site because a FEW of you really know your stuff..but obviously want to keep it all to yourself, it looks like yall would rather give eachother crap about the condition(or lack of) their car.but not one f####n time has any of you really offered some good advice to me on my car...wow what it could be if everyone passed on thir knowledge in a oldfashioned sort of way.....im sure thisll get me booted but so what ...ive got better from the v.w. crowd down the road....

RED85TPI

Dude... you are in the wrong thread to ask a question about your LT1 leaking oil. This is a thread about adjusting your TPI.

I'm sure if you search and post in the correct area, you will get plenty of help.

Good Luck!