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Unread 08-14-2013, 05:28 AM   #31
gmakra
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Here's my take on this, the Howell TBI is limited since the system is stripped down to bare bones sensors and does not control the ignition.

The questions I have are this
1. Are you running the stock heated manifold?
2. What is your ignition timing set at idle?
3. Have you removed the TPS or IAC?

Castle Rock Colorado is higher than 6000 feet above sea level and I don't believe the map sensor is parametrically compensated.

So given the information you described I would look at a couple things.
One check for vacuum leaks and make sure that you do not have any. 90% of the Howell problems are caused by vacuum leaks.
Two have you played with TPS or IAC if so you need to reset those and here are is how it's done courtesy of third Gen.org

IAC and TPS Adjustment
Tom Keliher Mar 31 2006 - 3:07pm
Idle Air Control

Tools needed:

Torx bit # T-20
Paper Clip
Small Punch

Take the paper clip and open it up and form it into a big "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' pins.

Turn on the ignition, but don't start the engine. Wait 30 seconds. Now, go remove the connector from the IAC.

Start engine. You are now going to adjust "minimum air". There is a Torx screw on the side of the throttle body. This is what needs to be turned to adjust minimum air, or more commonly known as "idle speed". It comes from the factory with a protective metal cap over it. If the cap is still there, use a small punch to knock it out. Set the idle speed to 450 rpm, rotating the Torx screw clockwise to raise rpm, and counter-clockwise to lower rpm. Once the idle rpm is set, turn off the engine.

Re-connect the connector onto the IAC. Start engine. Idle speed is now once again governed by the ECM, but your idle should be smooth and steady, approximately 600 rpm in Drive (for unmodified cars).

If you set an SES light by having the IAC disconnected, then after shutting down the engine disconnect the negative battery terminal. Wait 5 minutes. This will clear the ECM of all trouble codes. Re-connect the battery and drive the car for 20 minutes to allow the ECM to relearn your driving style.
Throttle Position Switch (TPS)

Tools needed:

Digital Volt-Ohm-Meter (VOM)
Jumper Wires (make your own)
Auto Xray Scanner (if available) will eliminate the need for VOM and jumper wires.

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

With a scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.075Volts

With VOM and jumper wires: disconnect the connector from the TPS. Using your jumper wires, make a connection allowing some room for the VOM terminals to contact the jumper leads and read the TPS voltage.

If out of spec, loosen the two 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, that could mean a bad TPS switch and could be a cause of stumbling and driveability problems.

After setting the correct voltage, turn off ignition switch. Remove jumpers/scanner and reconnect the TPS connector as required.

At your altitude you should be running additional advance, I can't give you a specific amount to advance your just going to have to advance of a few degrees of the time Till the engine starts running nicely.

Another thing you should do is get WINALDL and purchase or build the cable so that you can run it on your laptop and see what the Howell kit is doing. Here is the link

http://winaldl.joby.se/

With this setup you can see exactly what's going on and eliminate the guessing.

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Unread 08-14-2013, 05:29 AM   #32
gmakra
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Correction to above " I dont belive the Howell Kit is Barametrically compensated"
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Unread 08-14-2013, 06:18 AM   #33
Gasman303
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Quote:
Originally Posted by 86cj74.2L View Post
With a stock manifold that's where your O2 sensor is, correct?

Cheep sensors make for a cheep fuel injection system know matter who put the package together and said its for your jeep.

A original GM map is one thing you should have. Any GM car or truck will have one. Get a few spares next time you go junking. (As long as GM is stamped on them)

If the previous owner installed the Howell and never got it running correctly you may need to go over the whole thing.

Are you still using the heated intake manifold and the grid heater?
Yes, this is the original heated intake manifold and the grid heater is hooked up!

I just purchased a map from autozone but have yet to install it!

So when buying iac, map, 02, tps sensors would going through GM parts be best or ac delco ok?
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Unread 08-14-2013, 06:20 AM   #34
gmakra
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AC Delco is GM and you should be good.
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Unread 08-14-2013, 06:27 AM   #35
Gasman303
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Quote:
Originally Posted by jayzcj5 View Post
Dude you need the SES light hooked up for sure. Any 12v light socket with 2 wires and bulb will work. Also you need to check for vacuum leaks, if you have a slight vacuum leak your MAP sensor will be relaying bad info to the ECM thus making you run rich. I just went through this getting my buddies jeep running with the Howell set up. I had a huge vacuum leak because of the intake manifold hitting the new header just enough in 3 spots to not make a proper seal to the head. I was fouling plugs in less than a minute and the jeep would die. When i pulled the plugs they were black as black can be.
Look into it but a scan tool would also be a big help. You will figure it out.
Quote:
Originally Posted by gmakra View Post
AC Delco is GM and you should be good.
Thanks for all the useful information, I've got my work cut out for me but I'm determind to figure this out once and for all
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Unread 08-14-2013, 07:14 AM   #36
Gasman303
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As you can see the 02 is sooted up again but I've noticed that it also has soot/carbon built up on the side of the 02 body that sits just above my exhaust collector? Could an exhaust leak out of my collector also cause it to run rich? I would think not because its on the down side of any vacume lines and 02?!!
image.jpg  
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Unread 08-14-2013, 07:48 AM   #37
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Do you have an exhaust leak or are you just grasping for straws?

Regarding the LED check engine light, I've been running one since installing a Howell system in 1998. Yes it's a diode, but it doesn't have anything to do with the EFI system other than to light up.

Howell's comment about your tach acting erratic was an odd one. The tach is just reflecting how the engine is running as a result of poor fuel delivery (the EFI!). I could see them telling you that if it were running smoothly and the tach was bouncing around, but that's not the case here.

GMakra gave you some good info to start an actual diagnosis. Your timing should be somewere around 10-12 BTDC. I'm at 6300ft (just east of Parker) and it's true that you do need additional advance because of the altitude.
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Unread 08-14-2013, 07:54 AM   #38
jdarg
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What ECM is the Howell TBI based off of?

You should be able to make a cable that goes from the ALDL port to a standard computer serial port for $5-10. That will give you a constant feed of all the operating parameters while the motor is running, several times per second or more depending on the ECU family, so you can figure out exactly where the problem lies. This allows you to see timing, fueling, etc. in realtime.

Throwing parts at a bad tune won't get you anywhere except a little lighter in the wallet.

The GM ODB1 system DOES automatically adjust for altitude. Its carbs that have issues with that, not fuel injection. If Howell is giving out custom chips specifically for those vehicles, that tells me either they aren't using all the sensors they should be, or they aren't doing it right. As a rule, pre-burned chips are never quite correct, just "good enough", maybe worse.

With a datalogging cable and a $50 chip burner, you can be burning your own chips that are actually tailored for your engine and what it wants. Do some research, there's an over abundance of info out there on web if you want to learn and invest under $100 bucks. GM fuel injection is not a "black art" like it is for some of the newer ECUs. It is very well understood by the community to the point where people have completely disassembled the code in the computers.
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Unread 08-14-2013, 08:03 AM   #39
CSP
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Howell uses the 1227747 ECM. The nice thing about burning your own chips is you can add back the ignition timing controls like GM designed into it from the start. It just takes adding a few wires to the harness and modifying the distributor to work with the 8-pin ignition module. I did it to my Howell system a few years ago after a successful junkyard TBI swap into a friends CJ.
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Unread 08-14-2013, 08:48 AM   #40
Gasman303
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Quote:
Originally Posted by CSP View Post
Do you have an exhaust leak or are you just grasping for straws?

Regarding the LED check engine light, I've been running one since installing a Howell system in 1998. Yes it's a diode, but it doesn't have anything to do with the EFI system other than to light up.

Howell's comment about your tach acting erratic was an odd one. The tach is just reflecting how the engine is running as a result of poor fuel delivery (the EFI!). I could see them telling you that if it were running smoothly and the tach was bouncing around, but that's not the case here.

GMakra gave you some good info to start an actual diagnosis. Your timing should be somewere around 10-12 BTDC. I'm at 6300ft (just east of Parker) and it's true that you do need additional advance because of the altitude.
By using almost a full can of Carb cleaner to detect a leak I have found nothing! No high idle etc. I haven't tried a smoke test because I can't get the POS to run long enough! I'm just trying to touch all bases, I have never had to work on efi and after this I will become an expert at it right? This is how a person learns, I'm willing to learn man so give me some credit,

BTW I DON'T HAVE A LAPTOP TO BUILD MY OWN COMPUTER CABLE TO CONNECT TO!! I'm using a apple iPad most of the time, I don't think there's a cable attachment for that?
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Unread 08-14-2013, 10:59 AM   #41
86cj74.2L
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Yes if you have a exhaust leak at the down pipe it will allow fresh are into the manifold through a process called reversion.

But, saying that I don't think it would be capable of making your O2 sensor read .1v and stay there.

As mentioned before the Howell is just a GM TBI setup modified for your application.

You have a return line for fuel comming off the throttle body, correct?
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Unread 08-14-2013, 11:15 AM   #42
CSP
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Quote:
Originally Posted by Gasman303 View Post
This is how a person learns, I'm willing to learn man so give me some credit,

BTW I DON'T HAVE A LAPTOP TO BUILD MY OWN COMPUTER CABLE TO CONNECT TO!! I'm using a apple iPad most of the time, I don't think there's a cable attachment for that?
Whoa, easy there! Nobody else knows what you know or what kind of equipment you have available.

You're not going to detect an exhaust leak with a can of carb cleaner or with any of the other methods used to detect a vacuum leak. An exhaust leak will show up as streaks of sooty exhaust residue around the leak point and/or noise.
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Unread 08-14-2013, 07:30 PM   #43
Gasman303
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Replaced o2 sensor, tps, iac and Ses light! The jeep now runs like a Champ!! Drove it for 20 minuets with no issues, idled for 10 minutes before driving

I'm not going to pay $220 for obd1 scanner so my buddy (automotive repair shop owner)45 minutes away says he'll scan it for me, with the jeep running good I don't want to take any chances. I also talked to Troy at howell and he thinks 13 psi is too much fuel, he thinks I can choke it down with a regulator or adjust the reg on the TBI to 11 psi so that it will lean it out a bit!

He also wants me to call and give him my parameters after it warms up to specs to see where it could use tweaking!

I still think after upgrading ignition system it will have a better spark to help burn better!
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Unread 08-14-2013, 09:36 PM   #44
86cj74.2L
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The O2 sensor should trim any fuel be it plus or minus based on the O2 sensor is feeding back to the PCM.

You really should have some way to troubleshoot on your own. What if your wheeling and something happens
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Unread 08-14-2013, 10:16 PM   #45
Gasman303
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Quote:
Originally Posted by 86cj74.2L View Post
The O2 sensor should trim any fuel be it plus or minus based on the O2 sensor is feeding back to the PCM.

You really should have some way to troubleshoot on your own. What if your wheeling and something happens
That's what I'm afraid of! I'm keeping my eyes out for a good obd scanner on eBay or maybe I'll get lucky enough to trade for one with extra camaro parts I have laying around
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