[kforrest]

bought a used 2006 ridgeline about 5 months ago, while driving a few days ago my car suddenly lost power while on the highway and wouldn't accelerate past 20 mph, with no check light, but vtm4 light is on.
I did a dtc scan which showed "p0300 random misfire", i changed the plugs, coils and checked the injectors, the cat converter, even the ecu but still cant find the problem, there are no honda dealers where i am so cant take it in for full scan.
dont know if anyone has had the same issue or heard of this issue, that can offer their advice on how to approach this problem. u can contact me at [email protected] directly or reply to my post.

 

[gberan]

Check your 4 wheel lock system. If the light is on it is energised and your cannot exceed 20 mph with the wheels locked.......hope this helps

 

[chiph]

The VTM-4 Lock will automatically disengage about 19 mph or so. It won't limit you to that speed.

OP -
Since you changed the plugs, coilpacks, etc. that eliminates a lot of what can cause a P0300. I would look for a chewed-up wiring harness, like from a squirrel, especially on the injectors. I'd also look for an intake air leak - take the plastic cover off the engine and look for loose bolts, etc. on the intake plenum.

And I'd also check the battery voltage. Old & weak batteries cause many odd problems. I just replace mine now every 3 years just to avoid the problems they cause on modern computer-controlled cars.

One more thing to try - disconnect the negative battery terminal for about 10 minutes, then reconnect with a minimum of sparking. This does a computer reboot.

Chip H.

 

[zroger73]

Deleted. Chiph beat me to it.

 

[kforrest]

Did a walkthrough of the wiring harness today and checked for vacuum leaks with nothing found no leaks. What else can I check. Also did a compression test and the front banks read 125psi and the back banks 175psi. Could this be an issue.

 

[Dnick]

Did a walkthrough of the wiring harness today and checked for vacuum leaks with nothing found no leaks. What else can I check. Also did a compression test and the front banks read 125psi and the back banks 175psi. Could this be an issue.

YES!

Is #6 (far right.. toward driver... on front bank) also low??? I ask because it is not usnusual for two adjacent cylinders to be low (e.g. 4&5). If that's the case, you could have a bad head gasket, or possibly cracked head between cylinders. not what you want to hear, but that's why you do the compression test.
It's not terribly low, so I'm surprised it would cause the problem you described, but it is significantly off from the others, and that's what you typically look for with a compression test. Good Luck.... not sounding too good for easy fix. I'd check compression again & get more precise numbers... those sound like pretty round numbers for all 6 cylinders.
Hopefully you'll find bad injector pump or ????

 

[kforrest]

Yeah doesnt sound like what i.wanted to.hear, since the coolant and all fluids are the same color i was assuming the head gasket isnt the primary cause of the problem.

 

[Dnick]

Yeah doesnt sound like what i.wanted to.hear, since the coolant and all fluids are the same color i was assuming the head gasket isnt the primary cause of the problem.

Keep in mind that blown head gaskets / cracked heads come in all flavors & colors, not all of which break through to coolant or oil passages.
If you have a compression leak from cylinder to cylinder (#4 to #5 for instance), then you'd loose power w/o co-mingling fluids. Hope it's not your case, but you really should find out why #6 is also low???
Possibly just mis-read when tested (I only say that since all of front bank are the same & all of rear bank are the same.... sounds too coincidental).

EDIT: UNLESS ! ! ! ! It just occurred to me that there "MAYBE" some function of the VTEC that is on the fritz???? This comment is totally speculative, but since your front bank & rear bank compression readings are as they are (front same but different from rear same), presuming the readings are correct; the one think I can think of that 'might' effect an entire head/bank (compression-wise) is the valve timing mechanism (VTEC). This is a clue you might want to follow-up. You would think that you'd get a code if something were amiss here, but I thought I'd throw out the notion in any case. Again, Good Luck!

Notwithstanding all of that, I would still closely examine your fuel injection system. Also check for blocked exhaust (collapsed cat converter).

 

[interpon]

Did you do the chiph recommendation? Battery reset?

 

[Dnick]

^^^^^^^^^
ditto that if you haven't already ruled out "limp mode" causes. You might do yourself a favor by searching "limp mode" in search bar above on blue stripe? You might just find something.

 

[chiph]

There have been VTEC issues in other Honda models caused by poor oil quality (the VTEC unit is oil-driven and doesn't like getting sludged up), and low oil level (make sure oil is closer to the top hole in the dipstick than the lower)

Chip H.

 

[kforrest]

Did the battery check and the battery is good 13.6v, I was doing some research and found something in the repair manual that said its the torque converter, going to replace that and see what happens.

 

[zroger73]

Did the battery check and the battery is good 13.6v, I was doing some research and found something in the repair manual that said its the torque converter, going to replace that and see what happens.

Good lord. What a [possibly futile] relatively major attempt at a repair!

By the way - just because the battery voltage appears within acceptable values does not mean the battery is good. Many owners have experienced weird problems with bad batteries that tested "good".

 

[Ourfarm09]

P0300 is a Pain in the @ss to diagnose and fix because it can be caused by just about anything. I have the same issue on my van that I have been chasing for 4 months now.

 

[MikeT]

Did the battery check and the battery is good 13.6v, I was doing some research and found something in the repair manual that said its the torque converter, going to replace that and see what happens.

You're better off replacing the battery first. Hell of a lot easier than the torque converter.

 

[kforrest]

Ok, i appreciate all the input i received and thanks to the person that sent the manual it helped a lot.
i finally figured it out today and it was the cat converter...didnt realize at first there were three converters that ran on these. And it was the gas that gave the misfire codes and caused the converter to go bad. Didnt change them btw i just "dug" it out and it seems to be beeathing a lot better now. Again to all who tried to help thanks a million. ?

 

[Dnick]

Glad you finally sorted it out. Blocked exhaust is never the first thing that comes to mind, only because it happens so infrequently, but we should be thinking of that with these kind of symptoms (runs but won't "go").

Happy Trails!

 

[IanRTL]

Ok, i appreciate all the input i received and thanks to the person that sent the manual it helped a lot.
i finally figured it out today and it was the cat converter...didnt realize at first there were three converters that ran on these. And it was the gas that gave the misfire codes and caused the converter to go bad. Didnt change them btw i just "dug" it out and it seems to be beeathing a lot better now. Again to all who tried to help thanks a million. ?

Glad it was a relatively easy fix. Always use high quality fuel and ensure you let the truck warm up enough to burn all of the deposits off of the cats. A 10-15 mile or 20+ minute trip at least a few times a week is good. I only drive 3.3 miles to work and back, so I ensure to get her out on the highway a few times a week. I like to get it above 4000 RPM at least once and week, too. Putting the throttle down while on an onramp does that sufficiently.