2F TBI help (1 Viewer)

[pvalchev]

I recently acquired a very fun FJ40 with a '78 2F and (what I think is) the Downey TBI kit (w/ the GM computer from 4.3 engine). I drove it 600 miles and it did amazing, lots of power and I got 15 mpg on the highway maintaining 65-70mph with 37" tires, SOA etc. - highly exceeding my expectations (big hills of course mean going slower, but again, my expectations were low).

I've been driving it around for about a month, and now I do have a few things to figure out, and I was hoping you guys would have advice.

1) When it's cold, in the first couple of minutes, it idles pretty low (same as when hot) and sometimes dies. I live at 6000' and not sure if this has to do with it... but from my house I go up a hill, down the hill on the other side there is a stop sign at the bottom - every time I put it in neutral towards the stop sign at the end, the RPM's drop and the engine dies if I don't give it a blip on the throttle. Any idea what would cause this/how to fix it? Is there a temperature sensor that's perhaps not hooked up and it doesn't know the difference between cold and hot, so it's not giving it enough fuel when cold? Where would that sensor be located?

2) I get the occasional backfiring, it seems to happen when I'm under heavy acceleration and shifting from 3rd -> 4th. If I go over 3000rpm in 3rd gear, and I push the clutch in, it'll sometimes backfire (once). Any ideas why this happens? Or should I just live with it? (I do need to shift at 3000rpm due to a big gap between 3rd & 4th in the SM420..)

3) I was reading about the TBI setup here: http://www.tomquinn.com/lc/2f_fi/ - and it talks about someone having figured out the perfect PROM for the computer. I tried contacting the author and also the person behind http://www.olympiafj60.net/2f-tbi-carb-replacemnet.html but haven't had much luck getting in touch. I might already have a good setup so maybe I don't need to touch it (it was programmed by Turbo City who I understand are experts and sell their own TBI kit)...

4) I can't find the ALDL connector for the life of me (to hook up OBD I computer to read codes etc.) - any clues where someone would install it? Or perhaps it's not wired to the computer at all... I don't necessarily need to mess with it, but I want to be prepared to troubleshoot (I do have a check engine light wired on the dash).

Any other resources to recommend/read, apart from the two websites I listed in 3) above?

Thanks so much!

 

[Jerry D.]

Check out moates.net

Jerry D.

 

[lcwizard]

Replace your temp sensor first. A cheap and easy thing. It may solve your temp related issues. Probable mounted on the thermostat
housing ? I'm guessing if you let off the throttle for a second before shifting you don't get that backfire. It's a timing/mixture issue.
You would have to play around with the programming to change that. May not be worth the trouble if it's only occasional. You can always
just familiarize yourself with the conditions that make it happen and avoid it. I don't worry about occasional exhaust backfires so much as intake backfires. I like to avoid the intake ons

 

[terrx]

There's a couple ways to look at it. Is it running the way it was originally installed and tuned, or has something changed since then and it's running worse? The first will take more time and effort to fix. The second is arguably easier assuming it ran well at one time - without knowing too much about TBI you can essentially throw money at it runs the way it originally did.

If you can figure out what sensors it has that might help... O2 (heated or non-heated), CTS, TPS, VSS, spark, knock, etc.

ALDL is probably near the ECM, perhaps in the glove box?

 

[White Stripe]

Well just saying you have tbi isn't enough details for a diagnosis. If you have a system with less sensors you are going to have more bugs. The more sensors you have the less bugs. Do you have a speed sensor? Do you have spark control hooked up? If you don't know what these are or how to check, then you should probably take it to a dyno shop that has some experience with tbi and have them see what you have. My opinion is have all the sensors except knock sensor, and have it dyno tuned. Its kinda expensive to go this route, but it saves time and hastle in the end. Their is no perfect program out their someone has you can download onto a prom despite what you see in certain forum threads.

 

[CDFarmer]

I recently acquired a very fun FJ40 with a '78 2F and (what I think is) the Downey TBI kit (w/ the GM computer from 4.3 engine). I drove it 600 miles and it did amazing, lots of power and I got 15 mpg on the highway maintaining 65-70mph with 37" tires, SOA etc. - highly exceeding my expectations (big hills of course mean going slower, but again, my expectations were low).

I've been driving it around for about a month, and now I do have a few things to figure out, and I was hoping you guys would have advice.

1) When it's cold, in the first couple of minutes, it idles pretty low (same as when hot) and sometimes dies. I live at 6000' and not sure if this has to do with it... but from my house I go up a hill, down the hill on the other side there is a stop sign at the bottom - every time I put it in neutral towards the stop sign at the end, the RPM's drop and the engine dies if I don't give it a blip on the throttle. Any idea what would cause this/how to fix it? Is there a temperature sensor that's perhaps not hooked up and it doesn't know the difference between cold and hot, so it's not giving it enough fuel when cold? Where would that sensor be located?

2) I get the occasional backfiring, it seems to happen when I'm under heavy acceleration and shifting from 3rd -> 4th. If I go over 3000rpm in 3rd gear, and I push the clutch in, it'll sometimes backfire (once). Any ideas why this happens? Or should I just live with it? (I do need to shift at 3000rpm due to a big gap between 3rd & 4th in the SM420..)

3) I was reading about the TBI setup here: http://www.tomquinn.com/lc/2f_fi/ - and it talks about someone having figured out the perfect PROM for the computer. I tried contacting the author and also the person behind http://www.olympiafj60.net/2f-tbi-carb-replacemnet.html but haven't had much luck getting in touch. I might already have a good setup so maybe I don't need to touch it (it was programmed by Turbo City who I understand are experts and sell their own TBI kit)...

4) I can't find the ALDL connector for the life of me (to hook up OBD I computer to read codes etc.) - any clues where someone would install it? Or perhaps it's not wired to the computer at all... I don't necessarily need to mess with it, but I want to be prepared to troubleshoot (I do have a check engine light wired on the dash).

Any other resources to recommend/read, apart from the two websites I listed in 3) above?

Thanks so much!

Hi pvalchev,

Congradulations on your purchase-
ALDL is behind ash tray (remove ashtray 2 screws) should see the connector, also accessible underneath ashtray.
- I haven't driven the 40 since I sold it over 3 years ago, but I would routinely drive from sea level to 8,000ft without issue- occasional backfire 3rd to 4th (wide open)
You are correct, Turbo City in Orange Ca tuned & programmed (an additional PROM was also programmed & w/ the 40 when I sold it- (slightly different tune)
Check the voltage at Battery, only idle issue I ever had was due to a low Batt.

 

[pvalchev]

Wow thanks for finding this and replying, Chris! I love the LandCruiser community, so awesome to hear from someone who owned your truck 2 owners ago And finding that ALDL connector was evading me, now I know where it is, it'll be interesting to troubleshoot the idle issue. I checked the voltage at the battery and it's good, the truck will idle cold fine, the problem is only because I have a steep downhill from my house, and I am engine braking down the hill before a stop sign - it feels that the computer reduces fuel flow significantly since I'm coasting downhill (as it should), and then when I push the clutch in, it doesn't have enough time to react so it dies. Doesn't happen when the engine is warm or on the flats, only in this particular circumstance. Good to hear about the backfire being there the whole time, sounds like exactly how I experienced it, it seems pretty rare and I can just avoid it easily. I'll check in the parts box to try to find the other PROM, I did not see it when I went through the box.. might be worth a try since it's so easy to swap.

And thanks to everyone else for the sensor info, I spent some time last week and I think I have all the main sensors (O2, water temp, speed, etc), but going by a shop might be a good idea if I want to do some tweaking and to understand the system 100% (I just don't have any great shops in close proximity). It's fun to learn something new

 

[mtquivr]

I too have a Turbo City TBI conversion. Mine also stalls sometimes when coming to quick stop.
I think this is because Turbo City didn't use the VSS. When you take your foot off the pedal, the IAC tries to return to a stationary idle condition because it doesn't know the vehicle is moving.

From Jagsthatrun:

If you have a harness which does not use a VSS, you can add the VSS and properly connect the P/N wire on automatic transmission vehicles, or remove the P/N wire on cars with manual transmissions.

 

[Downey]

I too have a Turbo City TBI conversion. Mine also stalls sometimes when coming to quick stop.
I think this is because Turbo City didn't use the VSS. When you take your foot off the pedal, the IAC tries to return to a stationary idle condition because it doesn't know the vehicle is moving.

From Jagsthatrun:

You hit the nail on the head, The VSS works with the 02 sensor to control idle functions, and without VSS engine shut off is very common at stop lights. With that said, I'm amazed your rig is running so well without a VSS ???

 

[pvalchev]

I've been chasing some very intermittent misfires/weird issues in my truck this summer, that seem to only happen when the engine is cold. One of my theories is that it may actually be the intake manifold gasket leaking (see photos), and I can't tell if this is a stock 2F gasket, or something custom? Can anyone tell from this photo? Thanks for any insight

 

[B y r o n]

Starting fluid sprayed at the intake gasket area will generally tell if there is an intake gasket issue.