Re:Lag on Acceleration or Flat Spot

Hello, I have a 1999 Jimny, 1300 cc

Whenever i try to accelerate my foot flat on gas pedal the jeeps takes time to move off, or Hesitates, Especially moving off from a dead stop I have done basic things so far. (changed Air Filter, changed fuel filter & pump, cleaned throttle body, changed cam & crank sensor, cleaned fuel injectors, changed spark plugs, tested MAP Sensor...seems good)

I am suspecting the TPS Sensor, but i welcome any ideas and or suggestions as i am basically trouble shooting this problem on my own.

One thing is troubling, any scan tool that is plugged into the ECU dose not communicate, there is no information,

Because the scan tools doesn't work the mechanics don't want to spend the time to find out what the problem is.

Any Help would be appreciated thanks.

kinjit wrote: One thing is troubling, any scan tool that is plugged into the ECU dose not communicate, there is no information,

It won't on a 1999. They use a different protocol to OBD, even though the connector is the same.

Can't help with the rest I'm afraid, except if it is generally struggling and won't rev the catalyst is usually blocked, the one on the manifold breaks up and clogs the one under the car.

Do you know which scan tool will work on the 1999 Jimny? There must be a scan tool that will work with that protocol, i hope you can send me a link for that tool!

I mean it has a place to plug in so there must be one tool that will work?

And why doesn't my Dash show any errors? it's been that way for as long as i can remember. The check engine light comes on and once the jeep starts it goes out like normal, but i have never seen any errors show up.

Any info would be appreciated.

I Don't have a catalyst, just straight exhaust and a resignation on the end

kinjit wrote: Do you know which scan tool will work on the 1999 Jimny? There must be a scan tool that will work with that protocol, i hope you can send me a link for that tool!

I mean it has a place to plug in so there must be one tool that will work?

And why doesn't my Dash show any errors? it's been that way for as long as i can remember. The check engine light comes on and once the jeep starts it goes out like normal, but i have never seen any errors show up.

Any info would be appreciated.

I Don't have a catalyst, just straight exhaust and a resignation on the end

Rhinopower used to do one, and you could buy them through the shop, don't know why they aren't available any more.

Take a look at www.rhinopower.org/diag/cel.html

Hey Guys thanks for your responses.

Facade, that link is great, will try that this weekend.

Just to be clear, I have to stick the jumper where i would normally plug the scanner tool right?
My connector for the scan tool is slightly to the lower left of my steering column, behind the radio, kinda.

My ECU is behind my glove box

The connector to make the light flash the codes is behind the glovebox. Have a search on here, there must be someone with an older Jimny who has posted a picture of it.

However, if the yellow light isn't on, I doubt if there will be any codes.

If I recall correctly it's either behind the glovebox or behind the drivers side headlight. The rhino site has a guide I think

Sent from my SM-A505FN using Tapatalk

You seem to have tried everything apart from the coils and leads. I had something similar although I was getting a flat spot when driving along and starting off, but my fault was intermittent.
bryn

Hey Bryn,

I swapped the coils and still got the same result. I'm gonna have the Mechanic take a look, hopefully he can solve it will let you guys know the outcome. By the way how did you solve your flat spot issue?

Mine was a coils and leads issue.
Good luck

I’d agree with the above, it sounds like you’ve done some great work. From my experience on an old 98’ Z3 leads and ignition coils could be the culprit. A simple resistance test on the leads will suffice. As for the coils, they break down over time, not much you can do there other than hope for a cylinder specific misfire OBD fault code or bite the bullet and buy new.

Check for other simple things like vacuum leaks, pre and post Mass Airflow Meter. A leak pre meter will have a large affect on performance but not give you a fault code. (Unmetered air)