Intermittent loss of power/fuel

[tftech]

Hello,
I apologize ahead of time, but I have spent days searching and reading the forums trying to find a solution. There are a ton of really helpful and knowledgeable answers and suggestions, but I have not seen a firm solution. That is not to say that maybe there is no single solution, but hopefully I can get some narrowed guidance.


The worst part of my problem is that it is very intermittent, it does however seem to occur at about the same time of day.

In the morning as I drive to work the cars run fine expect that on the highway there seems to be a slight loss of power sometimes as if I was letting of the gas pedal for a second. Other than that it seems fine.

I can drive to lunch with no problems.

On the way home, however, it will do ok on the highway, but when I exit the highway it really starts to act up.

It will idle normally, but when I put in gear to pull away from a light it will buck and almost stall out. I have to keep the RPMs very low, about 1500, in order to keep the car running and shift into a higher gear as soon as I can just to keep moving. It will stall sometimes, but not often.

I did notice a noise from the fuel pump and pulled the back seat off. When it was happening again I felt the fuel line and noticed that it was kinda pulsing and seemed to have air or something in the line.

I am not sure if the Fuel Pump would behave this way or if something else if effecting the fuel supply causing this.


My plan this weekend is to change the front fuel filter, inspect the fuel strainer/tank, and blow out the fuel lines.

I have seen alot of people having a similar issue, but not a firm resolution yet and would really appreciate some guidance before I spend too much money on the issue (would not make wife happy).


The oddest thing is that at this point it is only happening on my home from work. What would possibly behave in such an intermittent way?

Please let me know if I have forgotten some important information as this is my first forum post.

Thank you ahead of time for your help.

Car is a 1992 MX-3 1.6l base model
Recent actions:
Plugs changed
Wires changed
Injectors Cleaned
Cooling system check and flush
Air Filter checked

[shameem]

Two more sensors to check/change - O2 sensor and coolant temperature sensor (there are 3 CT sensors - you only need to check the one right by the injector).

Make sure there are no minute cracks on the intake tube (that can widen with heat). If you are not sure just duct tape the whole thing - atleast until you rule it out.

Make sure the distributor cap and rotor are ok.

Reset TPS and clean up the TB with seafoam....

If you have any engine codes - http://www.mx-3.com/phpBB3/viewtopic.php?f=24&t=65390" onclick="window.open(this.href);return false;

[tftech]

Thank you very much.

That is the other strange thing is that there are no engine codes. I would think that something causing such a drastic change in performance would cause a code.

Sorry to sound stupid, but what is the TPS?

Thank you very much.

[OldMan]

The TPS is your throttle position sensor. It is located on the throttle body. A little plastic black box with 3 or 4 wires going to it, depending on type of transmission. Yours is most likely a 3 wire as you indicated you have a manual tran.

It could very well be the strainer in the fuel tank. However when I had problems with mine it was a little more consistant than what you are describing here. There are 2 types of strainer available. One is shorter, more square, the other is longer and rectangular. Get the longer one and install it. This will avoid the problem of insufficient fuel when your tank gets lower in fuel.

OldMan

[tftech]

-----Update-----

On the way home today it started even a bit earlier and I had to exit the Highway before I normally do. It was actually starting to lose alot of power while still on the Highway. I nursed it to an Auto Store before my house to buy some Carb Cleaner to test the vacuum hoses while it was misbehaving.

After being turned off for a few minutes it acted a little bit better on the 5 block ride home.


I sprayed the Throttle Body cleaner around every hose I could find as well as the Intake hose between the MAF and TB.

I could not hear any noticeable difference in the idling of the car. I am going to take from this that the hoses are not the culprit.

So, I am going to continue this weekend with the plan on cleaning the fuel system and cleaning the TPS and TB as recommended.

Something else I remembered is that before the single wire to the O2 sensor came lose. It looks as if it had been repaired before and the crimp broke lose. The care behaved in almost the exact same way. It did though give an error code that I decoded with the help of the info in this forum. I will also try to replace that, but local auto stores dont seem to carry much for this car, so I will have to order online or find in a junkyard and hope it is good.

Thanks again for the help.

[Mi|<E]

Ive had the same sort of problems with my old B6 DOHC from the 94 mx-3 and now
with my brand spankin new BP where the idle is all messy for no apparent reason.
I figure since the entire engine was changed out its probably not the engine. So I
went over to clubprotege to see if any of them had any ideas. Here is what I found:



Thats the clutch switch part and apparently the spring wears out over time according
to some Mazda mechanic someone talked to. Picture and info courtesy of Johniec on
Clubprotege btw. Im just relaying info that may be useful. The part itself is 15 bucks
to replace and believe me id pay that to get rid of the damn idle stall crap that is
happening to my car.

Part number for the Protege is : LA01-66-490A

Im not certain its the same as the MX-3 part but im going to go ahead and try replacing
that anyway. No one has had much luck finding the idle stall gremlin so I hope this info
from Clubprotege is good. I'll be the guinea pig and see how it goes.

Here it is in the manual:

[tftech]

Thanks for the info and the picture to help.


Only thing that would make me think that it would not be something to do with the clutch is that even when I am fully in a gear the engine will still lose power. Are you having issues when cruising on the highway in 5th? If so, maybe it is the same problem.


The only good thing now is that it is less intermittent, It started on my way into work this morning.


I am going to try an O2 sensor as soon as possible as well as the checkup/cleaning of fuel system and TPS and TB.

[Mi|<E]

O2 sensor, TB clean and TPS adjust doesnt hurt. I think mine is more vaccuum
related because it seems to only happen when the clutch is in and I tap on the
brakes.

All the hoses are new so I suppose I'll go through em 1 by 1. Im also going to try
removing the intake hose to the valve cover. The valve cover side I want to replace
with an air filter and the intake hose side block off.

[shameem]

Im also going to try removing the intake hose to the valve cover. The valve cover side I want to replace with an air filter and the intake hose side block off.

Please do not block off the valve cover inlets - it's part of the PCV (Positive Crankcase Ventilation) system and if you mess with it - it will start dumping oil through the open hole due to pressure/vacuum build up inside the valve cover. Also do not remove the PCV valve.

As for your idle problems when clutch/brake is applied - the brake lights take up a lot of power (4 * 24w + 3 * 12w) - so try adding more grounds to the engine and clean up existing grounds - so current can flow easily. You can also upgrade your existing alternator (65-70 amps) with a v6 alternator (90 amps).

[tftech]

----- UPDATE -----

I decided to run as low on fuel as I could today so that I could inspect the tank. I made sure to carry a few gallons in a can just in case.

On the way to work it was as bad as ever. Bucking and jerking at anything other than an idle.

I almost did not make it home and it stalled a few times and I had to put just enough gas to get home.

I pulled the Fuel Pump assembly and this is what I found a pool of rust/gas. The screen on the fuel pump was coated in rust. Used a spoon and scooped up rust from the bottom of the reserve tank.

I am going to hit a local junk yard that I know has 2 MX-3s and inspect those tanks. If they are any good I will be bringing one home. If not I will have to clean.

I also pulled the TB to clean while I was at it and the gasket broke off.

Does anybody know of any other TB gaskets that will fit that the local auto stores might carry?

I am hoping this is the problem.


It might be a few days before I am done, but I will make sure to post an update.

Thanks for the help.

[tftech]

Pictures of what I found









Looks like I was running on rust

[shameem]

http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0280838061" onclick="window.open(this.href);return false;

For TB gasket - i think you have to go to the dealer or just uses a lot of rtv

Keep in mind you have to change the fuel filter (high pressure side) too. This rust *may not* be your problem since it seems too intermittent - but its good to fix the rusty stuff and if it ends up fixing your problem then hurray...

[Mi|<E]

Tftech - you can use Permatex gasket maker on the throttle body no problem or order a TB
gasket from any dealer. They will likely have to order the gasket and its about 5 bucks. Permatex
is 5-7 dollars at your local hardware store. (Get the oil resistant stuff its the same price as regular
and good to 400+ degrees Fahrenheit)


Shameem - Im not blocking the inlets, just changing them from intake fed to ambient air fed. What
I am blocking is the intake hose outlet to the valve cover inlet. Ive got crazy gounds like you cant
imagine and a 120 amp alternator. My engine is the BP keep in mind, not the B6. I think there may be
some vaccuum issues around the vics though, its dark and I cant see, its going to be addressed
tomorrow.

Can those rear lights be changed out for some LED's? Have you by chance
looked at the specific size of them and calculated the resistor that would be required for a setup
like that to not suck so much power?

There are 4 #1157 brake lights at 27 Watts
and 3 #921 center lights at 18.4 Watts
Thats a fair chunk of draw for such a small stock alternator.
Even mine has trouble keeping up, could be a ground. I'll beef up
the brake light grounds tomorrow and see what happens.

[OldMan]

You found the exact same thing in your tank as I did in mine. You most likely will find the same thing in the tanks at your local junkyards. You can buy a new tank online thru RockAuto.com. They range in price from $105.-$130.00. Or you can drop your tank and clean it out. I have been told of a type of sealant that you can apply to the inside of the tank once you have cleaned it, the sealant is supposed to stop the problem from happening again, but I do not know how well or if it works.

As for the throttle body gasket, you may be able to get one from your local parts store. I don't know if you have an Advance Auto Parts store where you live, but if you do they should have one. You would need to ask for a fuel system tune-up kit for your specific car.
You can also go online to RockAuto.com and order a throttle body gasket. If I remember right it is about $2.00 for the gasket.

You can as mentioned above use permatex gasket maker, but just be careful and don't use to much. You don't want to block any of the necessary ports.

I hope this helps you, and good luck.

OldMan

[shameem]

Can those rear lights be changed out for some LED's? Have you by chance
looked at the specific size of them and calculated the resistor that would be required for a setup
like that to not suck so much power?

I have something like these in my altezzas......
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0267039399" onclick="window.open(this.href);return false;
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0267223838" onclick="window.open(this.href);return false;