TBI again

[digger]

I've got it all buttoned up and have been driving it (not very far from home) and the timeing is still off a little bit but nothing that I can't dial in. My new problem is that it will not go over 45 mph. I checked the length of my new throttle cable and with the pedal all the way to the firewall it is opening the throttle completely. My next thought is to check and see if the injectors are putting out enough fuel. Other then no power, it fires right up and will go.

 

[Sharp38]

Digger, I just came across your post and don't have the history. Can you give some info on the engine and so forth. It sounds a bit weird that you cannot get over 45 mph with a WOT position on the TB.

Don WWW.wolfcreekrodworks.com

 

[digger]

Right on, Did a complete frame-off on a '75 FJ40. swapped out the carb for a Downey TBI conversion. Everything is installed and hooked up as far as sensors and fuel lines etc.... when I first fired it up, it ran awesome and still does, but as soon as I drove it it would sputter and back-fire. Today I messed with the timing some more and lengthened the throttle cable and drove it again. There's still a little back-firing but its not sputtering. The only problem I notice other then the slight back-fire was that there is no top end power. It will not go any faster then 45 mph. Low end is still good. When I floor the gas pedal, nothing. Jut a kind of slow acceleration.

as I posted before, when I floor the accelerator the TBI is opening all the way. I'm clueless as to what to check next.

 

[cruiserbrett]

well,
lots of things could be wrong...

I would start with fuel pump/lines. whats the psi at idle? whats the psi when it wont go over 45?

 

[digger]

Here's an update,I've been driving it around a little more, took it to get the alignment done, etc.. and can get it up tp 50mph. It still is slow to accelerate and has a weak top end. When I step on it to pass someone it back-fires. With no load on it and openning the throttle it sounds great. It had np power in any gear going up a mild hill (freeway over-pass). I checked the fuel pressure and it was fine. What do you master minds out there think? It is so close to being done, It's eating me up!!

 

[BDSeff1fitty]

do you have water in your gas or anything? when i road dirtbikes last summer in moab the bike i was riding had water in the gas and low end was fine but the minute i gave it gas and put it under load it would just spit and sputter and wanna bog out.

 

[digger]

No water in the tank, I cleaned the tank out durring frame off, and just filled it with new gas yesterday. I'm hoping the more I drive it the better it will perform. It seems the more I drive it the better it is getting. I do appreciate all the help from everyone. I hope that I will be able to return the favor to fellow mudders.

 

[malcb]

Do a check on the plug color, run under load, neutral, shutoff the engine etc. Your other thread about fuel in the oil suggested it was running rich.

Don't know anything about the Downey TBI kit but;

do you have an O2 sensor, is it working
how does the ecu it operate under acceleration - open or closed loop
whats the air measurement system airflow or MAP (manifold absolute pressure) sensor

I would do some checking before pressing on and seeing if it will come right - there is potential to do quite a bit of damage without really being aware it is happening.

 

[digger]

The Downey kit comes w/ O2 sensor, MAP sensor, etc... it is a complete kit. The only thing you need to supply is the throttle body a/ ecm. I pulled the plugs yesterday, they were fine. No fuel on them or discolor (not black). I do hear a vacum or air leak when it is idling, not so mush when I'm driving (doesn't mean that it is not there), but can't locate it. All my vac lines are connected or plugged. I know it is going to be something simple that I will kick myself in the a$$ over. I even checked to make sure that it wasn't in 2 low on the xfer case.

 

[Trollhole]

Have you reset the IAC?

Getting better as your driving it is the ECU trying to fix the issue. It can only do so much.


What is your PSI as asked above?

How about some pics?

Do you have an ALDL cable? Can you post some logs for us?

Have you done the timing correctly?

Is it thoving any codes?

 

[too tall]

timing?