1992 Samurai 1.3 FI

I'm getting a sputter and stumble at mid throttle when the engine is cold. If you go ahead and give it some gas, it will go ahead and go, but at mid throttle, it stumbles and won't accelerate. Once the engine is up to operating temp, it does great.

Here's what I've done so far:

      plugs
      wires
      dist cap and rotor
      IAT sensor
      ECT sensor
      Seafoam in gas
      Seafoam through vacuum into engine
      new fuel filter
      new gasket on Throttle body
      went over all vacuum lines with starting fluid looking for leaks

I'm fairly certain this has something to do with fueling.

About 30-45 seconds from startup while dead cold, it will drop from a high idle down to almost dying. Then after about 15 seconds of stumbling, it will idle back up to high idle until it warms up and drops down to normal idle.

When driving, it only stumbles at mid throttle while cold. If you go ahead and put your foot down, it goes on without any problems. This happens in all gears. Also, if you let off the throttle and then accelerate again (mid throttle) it will do fine for a few seconds before starting to stumble again.


Any suggestions would be greatly appreciated. I've exhausted all my resources.

Well I have to admit... I'm not very impressed with this forum so far. I've asked the same question twice in two different sections over the span of a month and a half and have yet to get a response. So far, both threads have over 50 views each and not a single reply to each. The other thread was also an intro thread by a new Suzuki owner with pictures and didn't even get a hello.

Turns out, I got it sorted out after a month and a half.

 

Sorry to see you didn't get any replies. I saw this thread, but after seeing what you had already done, I had no idea what to suggest. Not to make excuses, but many ppl are hurrying around for the holidays, & maybe same as me, didn't know what to tell you. That & a lot of views may be from guests, who can't reply. The new posts seem kinda quiet of late. You also have a somewhat rare setup in the 1.3 TBI, though as I understand it, it's very similar to the 1.6 TBI.
In any case, welcome to ZW & I for one am curious what you discovered as the cause?

Fuzz

I have a '91 EFI with the 1.6 8v conversion, and when I got it, it would start but had problems keeping it running and it wouldn't idle at all until it warmed up some.

You didn't mention it, but have you put the ECM in diagnostics mode and made sure that it is flashing 1-2? Using the codes that flashed, I replaced the ECT and O2 sensors and it has started up great ever since. Also check you valve lash if you haven't already. Also found that mine runs better with the 195 thermostat rather than the 180, especially in the winter. 

If you need the FSM go to http://acksfaq.com/ and search using the term 'fsm'. 

Well I have to admit... I'm not very impressed with this forum so far. I've asked the same question twice in two different sections over the span of a month and a half and have yet to get a response. So far, both threads have over 50 views each and not a single reply to each. The other thread was also an intro thread by a new Suzuki owner with pictures and didn't even get a hello.

Turns out, I got it sorted out after a month and a half.

 

I answered you on another forum that you posted it on.  I guess I could have copied and pasted my answer here too.

This is the first time I've seen the post, but I wouldn't of had any suggestions
except to add a turbo, seems to get rid of the mid range stumble for me.

Wild

I did look at it, but I didn't have a thing to say about it except you are working through it and that's what counts. When it comes to all this complicated wiring and stuff it gets difficult. And welcome to the forum