what is up dudes... any howell tbi info - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 11-08-2007, 12:44 AM Thread Starter
 
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what is up dudes... any howell tbi info

haven't dropped by in a long while how you guys doing?

on a howell tbi on a 4.2, for the third consecutive smog check my jeep passed HC PPM by one count ...

1. tail pipe is stove black.
2. plugs look good and even.
3. it does miss a tiny bit.
4. idle is low, a little rough but it doesn't die.
5. gets 13mpg.

got a new ignition module on it.

code flashes "rich condition"

I still need to check for clogged return fuel line, but
anybody got any new tips or tricks on the howell tbi?
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post #2 of (permalink) Old 11-08-2007, 08:30 AM
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Do you have it using an O2 sensor for closed loop operation?

I'd start with propane enrichment.

Spray it around the TB and manifold to make sure there are no vacuum leaks. (a leak on one cylinder can cause the rest to go rich and set the code.)

Do a search on here for "propane trick" and do like it says, idle and higher speeds.

Make sure there are no exhaust leaks ahead of the O2 sensor.
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post #3 of (permalink) Old 11-08-2007, 09:45 AM
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In Road test mode when does it flash rich? It should flash rich any time at idle... Have you put it in road test mode to watch it?
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post #4 of (permalink) Old 11-08-2007, 06:44 PM Thread Starter
 
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RRICH, I tryied you propane trick...I've sprayed propane around and didn't notice any improvment. and yes it is the CA legal kit, so it has the O2 sensor. and a speed sensor.

LEVE,
I'll try the test jumper again. but it just looked like a bunch of flashing to me
so, you are saying I should have long deration pulses at idel and short duration pulses at any RPM over idle?
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post #5 of (permalink) Old 11-08-2007, 07:44 PM
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The propane trick - you checked for leaks, but did you actually use it to determine if it's too rich or lean at idle or at speed?

If so, what did you find out?

Finding leaks is only part of using it. I suggest you read the rest of it.

With today's fuels, it's not easy to tell if it's really rich or lean without adding additional fuel - like propane.

Before condemning anything, you need to know for absolute sure what it's doing, your complaint could even be an ignition or timing advance issue.

The other way is to just throw parts at it till your bank account is empty.
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post #6 of (permalink) Old 11-08-2007, 10:05 PM Thread Starter
 
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so the propane trick is trickier then I remmeber ... oh well. I'm going to have to buy a new torch.

do yall know where I could get a in line fuel PSI guage. part of the howel trouble shooting proccedure is to make sure fuel ia about 12 PSI. jegs has a guage with barb fitting but its 3/8 and the howell gas line is 5/16. the line is kinda stiff so I don't know if I'll be able to jam it in there.
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post #7 of (permalink) Old 11-08-2007, 10:09 PM Thread Starter
 
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leve. what is your idle RPM? mine is about 600 .thanks.

howell mentioned that electrical noise from the ignition module can trigger the computer and make the computer think its at a higher RPM and give too much gas.
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post #8 of (permalink) Old 11-08-2007, 10:23 PM
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My ilde is at 850, as I've got an automatic. A manual transmission should be at about 700 to 750.

Short pin A to B the Diagnostic ALDL connector and start the engine. Now the computer puts the SES lamp into Road Test mode. You can monitor the rich/lean condition of the input by looking at how fast the SES lamp flashes.

Now when the SES lamp is flashing at the rate of about 2.5 times a second, you're in Open Loop. You'll see this happen at idle, and even sometimes when you're crusin' down the street and the engine is not working very hard.

However if, after the engine warms up, SES is Off all, or most of the time the engine is running lean.

If the SES is on most of the time... the engine's running rich.

See, it's pretty darned simple:

SES on most of the time = Rich
SES off most of the time = Lean

After you watch the SES for a while when the Jeep's moving you'll soon find that you can trust it. It's a good indicator of engine management and function.
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post #9 of (permalink) Old 11-08-2007, 11:42 PM
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He He - Thanks LEVE - seems I can never remember how to do that.

Remember - the light flashing is what the computer "thinks" is happening. Sometimes that's not "what" is happening. It's interpreted values.

Most anything that affects how much O2 gets in the exhaust affects it - timing off, initial or advance, or even just a bad plug wire or plug or any ignition problem causes less burning in the cylinder, and more O2 in the exhaust, making the computer "think" it's lean, so it adds fuel - rich.

Sometimes just changing initial advance 2 or 3 degrees can make a world of difference with them.

Howell uses several computers - they use what they can get from local wrecking yards - GM TBI's - but they will deny it.
Some are set to use different initial timing advances. Some might be set to use 0 degrees, some 4, some 8, some even 12.

Look on the ECM itself - find the numbers on it - look them up on the internet for the application it was used in. Then look up the base (initial) timing for that application. It may be different than what they told you to set it to.

Remember - the Howell people are electronics guys - harness builders, not automotive people. Every time I've tried to get help from them, they've proven they don't know about cars and how they work.

For instance when a guy called and told them the TBI didn't fit the manifold - bolts did, but it left a huge hole by the side of it - major vacuum leak. They him to fill it with silicone.
Car folks would know silicone won't stick with gasoline around.

Another time a customer of mine had been trading chips with them several times trying to solve a dead cylinder problem. They kept telling him they were re-programming the chips for him.
I replaced the bad plug, no more problem.
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post #10 of (permalink) Old 11-09-2007, 01:46 AM Thread Starter
 
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RRich, just an fyi... the howell jeep kit bypasses the built in timing control functionality of the computer. the timing is controled purely by a vac/mech advance distributor. on one hand.. its old school simple and on the other hand it gives up some HP.

in regards to "elelectronics guys"; when all you got is a hammer, every thing looks like a nail
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