My 89 RS LO3, 305 TBI. When I get on it at about 1/2 to 3/4 wot it wants to bog down a little at around 1800-2200 rpm and also at wot @85-90mph it starts to sputter just a little, but still noticable when paying attention. do i need some need injectors or do they need a good cleaning. My mods should not effect this at all. All i have is a open air element and SLP cat back(no cat). let me know what you think.

D

 

I think a good cleaning with some injector cleaner can't do any harm and will not make it worse than it is. Try it.
When I had my TBI off for the ultimate tbi mods, I gave it a thorough cleaning and I noticed a smoother idle and better throttle response after doing so.
Maybe you should try this,too. It is not a biggie and will take only 1 - 2 hours of time.
If you want to do it, just be careful and remove the TPS, IAC from the throttle body because a cleaner could do harm to them. Concentrate on the throttle body. Also don't soak the injectors and the fpr in the cleaner.

I forgot to mention that you should get new gaskets if you disassemble your tbi. You can almost probably reuse the fuel line o-rings but not the little white plastic washers in the fuel line fittings as well as most other gaskets.

Later,

Andreas

 

Good advice. i will take off my tbi this week and get a tbi rebulid kit then with new gaskets. One other question for ya, how long and hard was it to do the ultimate TBi mods?

 

Since I was not very familiar with using a dremel it took me 2 days. I also had to go to a shop twice and had to get new grind stones because I either bought not enough of them or I purchased the wrong ones (me little stupid, you know).
I first removed the throttle bore ridge, then radiused the edges and polished everything I touched with the grind stones.
Then I shaved the throttle shaft.
After that, I made an injector spacer from a 5mm aluminum plate, using the original gasket as a template. I also cut two additional gaskets, again using the template, out of 1mm gasket paper (I hope this is the correct term) and sandwiched the aluminum spacer between them. I then reinstalled the old gasket and the sandwiched spacer back on to the tbi. Oh,and if you do use an injector spacer don't forget to radius the throttle body where the fuel line fittings go into the injector pod . If you do forget it, you will end up like me, having to remove the tbi from your car again, disassemble it and do the radiussing(again me little stupid).
I did all this using a dremel and some 100, 150, 250 and 600 grit sanding paper to prepare the throttle body for the polishing with the dremel.
As you can see, due to the mistakes I made this went way off from being perfect. But if you can avoid some of the mistakes I made, it should be a lot less time consuming..

Later,

Andreas

 

But all in all the time you had spent, was it worth the diffrence in performance, gas mileage, and throttle response? It sounds fairly easy and not that time consuming, but me to also has that stuputidy problem to over com:lala:!!! LOL Thanks for your help i did also just print off your article on all this.

PS did you also use a TB spacer or just the injector spacer? I think both working together would cool the returing gas quite a bit?


D

 

Performancewise I honestly did not "feel" a difference. But the SOTP-meter doesn't seem to be quite accurate, does it? I also still have the peanut cam and the stock heads on the engine and afaik, the reworked tbi is supposed to work better in an rpm range that the stock cam doesn't operate in or doesn't make power in at all.
I haven't noticed any mileage gains so far but my style of driving is too inconsistent to make any statements about it. All I can say is, that my mileage hasn't suffered after doing it. My best numbers are still 210 - 220 miles maximum on a tank of gas in city driving and about 300 - 310 miles maximum on the interstate (autobahn) at speeds between 80 - 100 mph. These are best number that I usually do not achieve. I had to have a "lighter" foot for these.
Throttle response has improved noticeable both off-idle (this should be due to the cleaning of the tbi) and when driving and flooring the pedal.
I have _no tbi spacer, just the injector spacer. There have been different opinions and impressions from several people on the board on the effects a tbi spacer has. Since it seemed a little expensive to me, I didn't plan to use one just to find out it probably doesn't work as supposed.
Assuming it works, it should have its effects in the upper rpm range giving you small ( somewhere between 1 - 5) hp gains. Maybe you want to perform a search on this topic. There is plenty to read about it.
BTW, have you seen Pablo's article about how to perform the ultimate tbi mods?
You'll find it here:

https://www.thirdgen.org/newdesign/t...matetbi2.shtml

So all in all I find, that it has been very much worth it. If not for performance then for the fun I had doing all the stuff despite the troubles I had.
But this is a part of the game and you can learn a lot about your car... and yourself (regarding all the mistakes I made :-)).

Good luck and have fun!!!

Later,

Andreas