1991 3F-E De-Smog Performed
- Thread starter spdwaver
- Start date
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SUMMIT CRUISERS
SILVER Star
No big MPG changes here. First tank looks as though it may be up 5% in mileage. My wife usually looks to fill up at 210 miles. First tank after de-smog went to 220. MPG's are still painfully low at 11.8 (all in town driving), which are adjusted 6.8% up for my 33x10.5's. Need a few more tanks to confirm. I do feel better throttle response which I'm thinking can be attributed to lower intake temps due to shutting down the EGR valve to the intake. Cold air intake anyone?
I desmogged mine last weekend. Wife drove it for the first time yesterday and asked me what i did to the landcruiser. She said it ran better. Meaning smoother. I def like my idle better now. Mpg was just under 10 before desmogging. Will post when i fill up again to see what (if any) difference it makes.
First fill up - 10.87 / gallon
I am getting Code 71 now (EGR System), started 7 days after "de-smogging". I am going to undo to see if it alleviates the CEL.
I have put on over 100 miles and at least a dozen starts and the code has not come back after hooking everything back up.
bbs
hey i just did all the hoses i need to change the belt can i ride like this for a while before i put the new belt or it will damage something?
hey i just did all the hoses i need to change the belt can i ride like this for a while before i put the new belt or it will damage something?
I tried this mod out today. Just BB's, no belt replacement.
First impression is acceleration 'seems' better, but it was 50 degrees here today. I think the cool air played more of a part in that than the BB's. Replacing the belt is where the better throttle response comes from.
The main thing I noticed was the exhaust tone was different, not better or worse, just different (maybe smoother?). That led me to the exhaust tip and I noticed that the exhaust does not smell rich like it did before.
I will top off tomorrow, check MPG, and report back.
First impression is acceleration 'seems' better, but it was 50 degrees here today. I think the cool air played more of a part in that than the BB's. Replacing the belt is where the better throttle response comes from.
The main thing I noticed was the exhaust tone was different, not better or worse, just different (maybe smoother?). That led me to the exhaust tip and I noticed that the exhaust does not smell rich like it did before.
I will top off tomorrow, check MPG, and report back.
An update on mine. Even though I have an exhaust leak at the cats (well where they usually are, thats another fix). I can notice more feel uphill and from a dead stop. Nothing major. You mentioned the exhaust tone above. I do too notice a change in the way it resonates. I thought it would just be my leak, but at certain RPMs under load the tone is noticable. Not sure what RPMs off the top of my head though. I am half way through my tank so no milage yet. The truck sat for a week because the radiator top cap finally busted and I needed the time to install it. Two vehicles comes in handy. When I replaced the old belt with a new one (and the idle pulley hardware grrr) I could tell a difference in startup/idle. Quicker response mostly. Next weekend is the oil change and I should have milage updates. But since I was averaging 13 on my normal route, we shall see (15 if all highway).
Well Code 71 came back this morning so maybe it was just a coincidence when it showed after I "de-smogged". I've done a ton of reading on Mud regarding this code and now have a list of things to check. Gonna go through the tests in the FSM and see what I can find.
I live in Arizona, and so far as I know there are no emissions tests. I'm looking at totally removing the entire smog pump/ EGR system to make space for a 93-97 battery box for my '91. Is there any issue with flat out removing all of it? (I'm aware that means that I'll never be able to move the registration of this truck outside of a state without emissions requirements.) How is the gas mileage change as of now? I'm really curious because if there's a significant change, it's worth it for the next 4 years worth of Arizona living at the least...
Has anyone found a belt that allows for more than one pulley on the alternator to run?
Even with a minute change in gas mileage, it may be worth it for me, as I want to do a dual bat setup and that position is the best place....
Has anyone found a belt that allows for more than one pulley on the alternator to run?
Even with a minute change in gas mileage, it may be worth it for me, as I want to do a dual bat setup and that position is the best place....
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SUMMIT CRUISERS
SILVER Star
Appolyon, did the mod late this summer. Truck runs better (like it is cool outside). No exhaust gases pumped into the intake. Fuel mileage difference not really noticeable, maybe 5% better. Sorry, no help on your belt question.
I assume that you don't live in the Phoenix metro area? I do and my system is checked every year.
You would assume correctly... I live in Prescott...
After doing this mod, my truck actually ran slower and more sluggish. My 15 year old son, who is driving under a permit even noticed it. I am pretty sure that I did it correctly. One of my 6 hard pipes was full of rust and I had to put a paperclip in there to clear, then blow it out. I am going to wait a few days and drive it around, but I may be putting my truck back to where it was prior. I will attach some pics of my routing to see if anyone notices anything wrong.
3sacrwd: Any update?
Seems like everybody else here has had positive results, but my truck is getting about 14mpg on the highway (10ish in town or at the ranch), so I'm wondering what benefit I would get out of this?
Any long-term benefits or drawbacks to doing this mod? I vaguely understand what the function of the smog pump is, so it makes sense to me that bypassing that would be "healthier" for the engine, but I'm a little hesitant to go against what came from the factory.
Seems like everybody else here has had positive results, but my truck is getting about 14mpg on the highway (10ish in town or at the ranch), so I'm wondering what benefit I would get out of this?
Any long-term benefits or drawbacks to doing this mod? I vaguely understand what the function of the smog pump is, so it makes sense to me that bypassing that would be "healthier" for the engine, but I'm a little hesitant to go against what came from the factory.
Update:
Since my last post on 10/14, I have only ran three tanks of gas. No improvement in gas mileage. 'IF' there is an improvement in acceleration it is not worth mentioning.
Also, my check engine light came on today. I have not pulled the code yet but I'm certain it will be EGR related.
My next step will be to check my codes put everything back to stock and in the future go to a true de-smog and just remove all of the components.
EDIT: I did not replace the belt to bypass the smog pump so it makes sense that I would not see any improvement in acceleration.
Since my last post on 10/14, I have only ran three tanks of gas. No improvement in gas mileage. 'IF' there is an improvement in acceleration it is not worth mentioning.
Also, my check engine light came on today. I have not pulled the code yet but I'm certain it will be EGR related.
My next step will be to check my codes put everything back to stock and in the future go to a true de-smog and just remove all of the components.
EDIT: I did not replace the belt to bypass the smog pump so it makes sense that I would not see any improvement in acceleration.
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No. The only thing I did was the BB's
So, would doing the bb's and looping the two vacuum hoses without disabling the smog pump screw something up?... I just wonder if this would be like doing "half an oil change"?
Maybe that's a bad analogy, but in my admittedly under-educated "mechanic brain", it seems to me that one of the biggest benefits I'd get from doing this mod would be the fact that I'm NOT pumping hot exhaust gas into my air intake... tweaking the vacuum hoses is just something I'd do in order to trick the truck into running right without that evil smog pump feeding it poison.
Am I missing something?
(entirely possible - vacuum hoses and such are like Chinese algebra to me!)
?
Maybe that's a bad analogy, but in my admittedly under-educated "mechanic brain", it seems to me that one of the biggest benefits I'd get from doing this mod would be the fact that I'm NOT pumping hot exhaust gas into my air intake... tweaking the vacuum hoses is just something I'd do in order to trick the truck into running right without that evil smog pump feeding it poison.
Am I missing something?
(entirely possible - vacuum hoses and such are like Chinese algebra to me!)
?
