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Old 07-20-2006, 10:25 PM
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Tuning a 350 TBI help??

Howdy,

I have a little 350 TBI from what I think is a 88 Blazer in my mazda. Im not sure what vehicle it came out of exactly, but it's in now and has been a project I have been trying to complete for some time.

2 years ago I got it emission tested and it passed with no cats, then the car sat for 2 years being driven maybe once every 3 months to move it to a different part of our shop's lot when it needed to get moved out of the way...

Now, trying to get it passed emissions again, and it just won't pass. Ive run the old gas out, put new plugs, wires, cap, rotor and run fresh tank of gas with seafoam through it, and it got better, but I just can't get it where it needs to be.

Is there a way on the TBI to tune the fuel richness up or down at all?

Here's the readings Im getting now, which are much much better than the first attempt:

high speed:
HCppm allowed: 220:passes at 196
co% allowed: 1.2, failed at 2.65
co2%: 11.0

idle:
HCppm allowed 220: fails 323
co% allowed 1.2, fails 1.58
c02% 11.1


the results were much worse before, so at least it got better.

If anyone has any thoughts I would appreciate it!


N

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Last edited by NOok; 07-20-2006 at 10:31 PM.
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Old 07-20-2006, 10:42 PM
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could be your fuel pump or injectors they sell kits to rebuild the tbi u say its been 2 years since u last drove the car so that could be it hope this was sum good info
- tony
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Old 07-21-2006, 11:43 PM
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The "adjustment" for mixture is done inside the computer automatically using the o2 sensor. This adjustment (or learning) is undone (forgotten) when the battery is disconnected. Driving it around for a few days might help. Are you using the AIR injection system? Do you have headers? Where is the o2 sensor located? Do you have a VSS hooked up? What is the coolant temp?

Do you have a laptop? If so download WinALDL and make a cable to hook your computer up to the ALDL port (I hope you installed one!).
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Old 07-21-2006, 11:50 PM
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retard the timing to a little before 0 and run the tank down to 1/4 tank and add 1 gallon denature alcohol drive it around till you get to normal temperature do not shut the truck off while you are waiting cause the converter will cool down in fact what i do is hold the idle up right before they take the truck so the converter stays nice and hot ... rule of thumb the hotter the converter is the better your chances are of passing
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Old 07-22-2006, 12:58 AM
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Quote:
Originally Posted by kardoc
... rule of thumb the hotter the converter is the better your chances are of passing
Except when the car in question has no cat on it...
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Old 07-24-2006, 12:40 PM
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Actually the problem was none of the above.... I decided to start from the bottom and work up, starting with the timing.

turns out the timing mark on the crank dampener was off by about ten degrees. I scoped the cylinder so I could actually visualize TDC for the piston, and filed a new mark into the pulley, moved the angle gauge to zero, set the ignition timing correctly, and that was the start. Setting the ignition timing correctly was probably the biggest thing, but I wanted to make sure, so I did a couple of more things.

I bought a new O2 sensor just in case on the way home from the testing facility the first time, and added 20 oz of alchohol to the tank and got the following readings on the retest, not bad for a old v8 with no cats!:

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Old 07-24-2006, 01:39 PM
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Hey NOok, what state do you live in? I'm live in California and that wouldn't be smog legal over here. Where's you alternator?
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Old 07-24-2006, 03:17 PM
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Hello,

Im in Utah,

It's legal here becuase it is considered an upgrade over the original 86 emissions that were in there before. I am not sure if other states do that though.

The car came with a air pump / cats system before, and now it has 02 fedback fuel injection now, so the state will issue a certificate of exemption here if since that emissions system is considered an 'upgrade'. They do the first test at the state testing center, then from then on you can get it tested anywhere that does testing. You just have to have the little form form the state stating how it is to be tested, doesn't have to have an air pump etc. any longer. Even with no cats, has really decent emissions.

As far as the alternator, it's some checker parts store generic plain alt they recommended for the engine.

N
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Old 07-24-2006, 03:46 PM
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Geez, I wish California was like that. I will be going from TBI to TPI in my 89 Camaro. TPI makes more power, gets better gas mileage and is more smog friendly. I guess what I ment to say was where is your alternator, but you probably don't have it installed in that pic.
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Old 07-24-2006, 03:49 PM
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Quote:
Originally Posted by ta3ff
Geez, I wish California was like that. I will be going from TBI to TPI in my 89 Camaro. TPI makes more power, gets better gas mileage and is more smog friendly. I guess what I ment to say was where is your alternator, but you probably don't have it installed in that pic.
It looks like a short water pump that he is using so I would guess that it low mounted on the driver side.
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Old 07-24-2006, 06:37 PM
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Quote:
Originally Posted by Triaged
It looks like a short water pump that he is using so I would guess that it low mounted on the driver side.
yep, down on the lower driver's side.
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