Here is the deal...
I have a 91' LS/VTEC, works fine and has been running strong for 2 years now, a few weeks ago i'm driving as normal and all of a sudded it starts to stutter slightly like a plug wire came off but it still had most of its power. Funny thing is when VTEC comes on it runs normal. I tried setting my VAFC to 3000 VTEC cross over ans sure enough it is smooth as soon as vtec comes on. At the begining it would not do it untill the car had been running for a minute or so but now it does it all the time.

Here is what i have already tried:
new plugs
new plug wires
changed distributor
changed external coil
new fuel filter
checked engine grounds
checked TPS sensor voltage
checked for vacuum leaks

If you have any insight or have dealt with this before please post someting!!!

thanks.

 

maybe one of your injectors is jammed up and you can run some additive through there to fix the problem. it would make sense if hitting VTEC fixes the studder since it pours more air and fuel into the engine. just a thought

 

i have the exact same problem right now. i too would like to know. I have done everything GEN2 HYBRID has done except change my fuel filter but could that really affect it??

 

The fuel injector being jammed is what one of my first thoughts were and i ran a bottle of injector cleaner through with no resolve. The other thing was i have a nice tan burn on all my plugs. However, i still want to try changing injectors. Which injectors can I/ should I use? Are GSR injectors different that LS injectors? I,ve heard that LS are 240 and GSR are 270, is this correct?

Someone throw me a bone here....

 

Has a fuel pump or filter crossed your mind? Just a thought.

 

Check your O2 sensor output. It may be low, slow and lazy. In my experience, it caused my car to buck slightly, most noticeable at about 25mph in 3rd gear. It didn't set a CEL because the ECU will only code if it sees no output over a certain period of time. Low and slow fullfills that parameter. As far running normal in VTEC, the ECU resorts to a programed fuel map at higher throttle and ignores O2 sensor readings during that time. BTW, for what it's worth, the cheap generic Bosch sensors I've tried worked for about two weeks. The second one didn't work at all. I had to buy an OEM sensor through hparts.com for $106. It's been working fine now for almost 2 years.

 

i'm havving that same problem.. mine seems to be intermittent.. i have yet to change the fuel filter though.. let me know if you guys figure something out.. i was also thinking the Ignition Control Module might be going bad

 

Well, i have already changed the fuel filter, and usually fuel pumps either work or they dont is what i thought. Has anyone had any different experiences?

Also, about the O2 sensors, i am running my ECU in open loop mode (neither of my O2 sensors are hooked up) which means all the fuel maps are pre-programmed on the ECU. I dont think this is related to the issue however as i have run in this mode for 2 years without problems.

Is the ignition control module in the distributor? Is that the same as the igniter?

Any other suggestions would be appreciated.

 

yes its the same as the ignitor.. but someone just told me that if the ignitor was going bad then the car wouldnt run at all.. so i dunno

 

I have had a number of igniters go in the past and it never did this. Also, i tried a different disrtibutor all together of a car that works fine.

Any ideas would be great!!!!!

 

ttt

 

I'd look into having your injectors benchmarked.... only like $30 and this is probably where the problem is.

 

what is benchmarked??? seeing if they're spraying right and not clogged? where do you find places to do this?