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Discussion Starter · #1 ·
Here's another "hesitation and hard start" thread.... thanks in advance for reading on... 95 LS V6 143,000 miles.

OK, First off, the car is sometimes slow to start. Crank for 5 seconds, then again for 2 seconds, and it starts right up.

When driving, in any gear at WOT, there is a "skip" which goes away at exactly 4500 RPM's - kind of like a mini VTEC effect - and runs fairly smoothly up to redline.

I have changed the plugs, cap, rotor, fuel filter. Because of the weird 4500 RPM phenomenon, I have eliminated a clogged cat converter as the cause. I have also dumped a total of 10 bottles of dry gas in the tank - I highly doubt that there is any water in the system or injectors.

I have had this trouble since I bought the car in May of this year - all the replacement parts have helped but not eliminated the situation.

All vacuum hoses are on - no leaks.

The "studder" gets worse as the motor heats up (the MX-6 seems to really run hot, insufficient engine bay cooling, I think a lousy design).

So:

1. Is it the distributor going bad?
2. A throttle position sensor? (sending the computer a lousy value that it ignores at 4500 RPM?)
3. The timing being retarded?

*help* and thanks for the replies.
 

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Had the same prob on my 93 after installing a CAI turns out the hose clamp on my Air Flow sensor was not tight enough. Every time the engine would heat up the rubber would change size and allow air to leak . MX-6 's are very fussy about air. any leak no matter how small can cause problems. hope this helps
 

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isnt 4500 a VRIS point?

i suppose since youve checked 'everything', youve done the paper test too.
 

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I just checked, the VRIS point is at 4250, which likely reads about 4500 on the tach. VRIS #2 would be at fault for a hiccup here.

As far as the poor cooling, I'm afraid I'd have to disagree with you. How can the cooling system be poor, plenty of people are making double the stock whp with barely upgraded systems, and not having much trouble.

If the car is near stock, it should run plenty cool as long as the cooling system is in good condition.

The timing should be fine.

The hard start issue could be disty related, especially as you mention that it gets worse as the car gets warm.

At this mileage, the TPS should be checked, though I doubt its at the root of your drivability issue.
-Garrett
 

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Discussion Starter · #6 ·
Thanks for the replies.

I did some reading on the VIRS system, and it sounds like this system is the trouble. I am Honda fluent, and mechanically inclined, but do not have much experience with the MX-6 V6. I'm learning as I go; thus logging on here.

A couple quick responses:

1. What the hell is the paper test? Do I have to fill out some sort of form? :p I don't know what this refers to. And as for checking everything, I checked the basics that would cause a problem that could have been easily diagnosed.

2. The cooling system isn't at fault (I've never had trouble with it) but I mentioned that the "under hood cooling" (ie. engine compartment airflow) was poor - I am on my second alternator because of this.

Anyway - I have a sweet parts donor up the street at the junkyard with 40,000 miles... I am going to check the service manual and start replacing the solenoids, and see if that helps.

What is involved with checking the TPS? Does it drift over time?
Where is VIRS point #1 (RPM)?

The distributor is still working... that will probably go next :)

(Iguana - the piping is tight and apperasto have a good seal.)

THANK YOU - will report back ASAP.
 

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your tps runs off of a preset voltage limit and as ware occurs the actual output changes causing a sparatic idle and things like that

you said u have a service manual...... check what the voltage is supposed to be... then compare there are two screws on the sensor that allow it to pivot for adjustment.
 

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Discussion Starter · #8 ·
The search feature is great ;) I found alot of answers to the questions I had........ duh on me.

Will get to this tommorow.... car goes great at exactly 4200 or so RPM's..... it must be an actuator or solenoid (I am suspecting the passenger side VRIS #1).

Posted elsewhere on this board:

Engine Speed (RPM)| VRIS Plate 1| VRIS Plate 2

up to 3250 |Closed |Closed
3250 to 4250 |Open |Closed
4250 to 6250 |Open |Open
6250 to 7500 | Closed |Closed

So, my problem is between 3000RPM's and 4200RPM's - and it croaks out above 6000 - looks like the #1 VRIS unit isn't working.

It would be cool to dyno the car and then see how much HP is gained by this stuff working correctly..... :cool:
 

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Discussion Starter · #9 ·
Well, now I've done *most* everything :)

I started to methodically check each sensor that I though might have a problem.

MAF - no problem. Checks out OK.
TPS - no problem. Check OK.

VRIS 1+2 - no problem. They both click when power is applied to them. All vacuum hoses on.

EGR - not officially checked but I don't have problems at idle.

BUT - when the car is on and idling, the Passenger side actuator is "on" - is this normal?

Replaced air filter - a tad of an improvement here.

This post caught my eye: http://www.mx6.com/forums/showthread.php?s=&postid=594938#post594938

I am now trying the Chevron Techron route...... I swear it's dirty injectors.
 

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96IntegraRS said:

VRIS 1+2 - no problem. They both click when power is applied to them. All vacuum hoses on.

are there holes in the diaphragm? is there a vacuum signal at the solenoid? hows your vacuum tank and check valve? how much vacuum did it take to actuate the vacuum motor?
 

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I can't believe the gurus here haven't asked you this... but have you even attempted to pull your codes as of yet?

I mean if you haven't, then try doing so!!! A light doesn't have to come on for the computer to store a problem code.

Sounds to me like your VRIS#1 Solenoid is bad. It happened to me when I had my 6, and would not accelerate very hard and just felt laggy until about 4500rpm or so. Once this hit though, it felt like a VTEC system and I was given a GREAT amount of top end power.

My suggestion is to replace this. You check the solenoids by measuring the resistance across the each one. If it is somewhere in the neighborhood of 10's of kilo-ohms you are good. If you see an open circuit, like Mega Ohm range, then it is bad!!!

Yoru spark is fine!!! Your fuel is good to!!! You have no driveability issues at lower rpms, and the car settles out at higher rpms... a dirty fuel injector would NOT act like this.
 

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Discussion Starter · #12 ·
Stage36:

are there holes in the diaphragm? no - they are both good.
is there a vacuum signal at the solenoid? yes, on both.
hows your vacuum tank and check valve? not sure where this can is..
how much vacuum did it take to actuate the vacuum motor? didn't measure PSI but sucking in using a spare vacuum hose was no problem.

Originally posted by Stingray77:

A good way to check this to unlplug the solenoid at idle, and to plug it back in, you should see the actuator arm move in and out.
You can also check solenoid #2 by using the #1 plug to see if the actuator works.
Just to clear things up VRIS #1 is OPEN AT IDLE! Only when under load it will the VRIS function as Mike 94's web page states.

According to this, both of the solenoids are working. I unplug #1 and the actuator "closes" and "opens" when the harness is reconnected.

BUT - when I probed the resistance across the solenoids, the left unit was tempermental. I cleaned the contacts..... and they both seem to be working correctly.

Just went outside to check the codes. Pulled up:

10 Intake air temperature sensor (IAT)
12 Throttle position sensor (TPS)

These are codes that were thrown earlier because of my testing.

No ECU codes of any signifigance.

Anyway - I'm going to find the solenoid new, buy it, and throw it in - because it was sketchy during testing, it may well be the problem. Again, there is a studder during acceleration - feels like a cylinder is missing.
 
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