SERIOUS PROBLEMS?????

[arnoldv]

1991 Mazda Navajo LX, 110,000 Miles.

Brought it in for a tune-up 'cause the car was rough idling. Still didn't solve the problem, so they ask me if I want to do a computer test to see what's wrong. They suspect a clogged fuel injector. After I start the car from the shop, I noticed the idling is even worst. I didn't think it was a big deal, so I left the shop. So I drove on the freeway, shift to Overdrive at 55 mph, the engine shakes when I step on the gas a lot. When I shift to Drive at 55mph, the car shakes once. BTW, I use Premium gas(91).

Now my ***#ing car is worst than ever!!!!!

Other problems before tune-up:

Temp Gauge (doesn't work)
Oil Gauge (doesn't work)
Fuel Gauge (doesn't work)
Batter Gauge (moves a lot when cold)
Oil Leak
Brakes (sqeaks and grinds)
Suspension (sqeaks and noisy when not on smooth road)

Probably lots more!!!

I don't know jack about fixing, maintain, buiding cars. Basicly I'm a noob!!

Any help would be appreciated.

 

[JDraper]

First off, welcome to the board!!!! You'll find a lot of info about how to fix stuff on your truck here. You'll also find lots of ways to SPEND MONEY on your truck too !!

As for your problems:

It's possible that you have a clogged injector. That would cause it to run rough. I'd also check the spark plugs to see what condition they are in. A worn out or damaged plug would give you the same type of rough running condition.

To have that many gauge problems at once leads me to think you have a bad electrical connection on the back of the gauge cluster. The battery gauge moving a lot may mean the battery is getting weak, or the voltage regulator is going.

Oil leaks just means the truck is marking it's territory !

You should probably check out how worn your brakes are. If they are grinding, you may have worn out the pads and be damaging the discs and/or drums.


Suspension creaks are kinda normal.

You don't have to run 91 octane. The computer in the truck is set up for regular fuel grade, and running high octane won't do anything for it.

I'd suggest you go out and buy a Haynes or Chiltons manual for the truck (about $15-20 at most auto stores). They are written for the home mechanic, and have a lot of info in them on what you can do to fix your truck, or at least give you enough knowledge to know if a mechanic is trying to rip you off.

Good Luck and Welcome!!

 

[arnoldv]

Originally posted by JDraper

You don't have to run 91 octane. The computer in the truck is set up for regular fuel grade, and running high octane won't do anything for it.

Actually I feel more power from using 91 octane.

From original post:
I drove on the freeway, shift to Overdrive at 55 mph, the engine shakes when I step on the gas a lot. When I shift to Drive at 55mph, the car shakes once.

Could it be the transmission?

Thanks!!!!

 

[Jason_25]

arndoldv, the reason you feel you're getting more power from 91 is because your engine isn't performing correctly. Have you tried to clean your MAF? Once you do that, you should probably be able to run 87 with the same amount of power as before.

 

[SanDiegoExplr]

are you running a v6 or a v8? Ive heard people say that its not good to run high octane gas in our v6's because it leaves more carbon behind and can mess up stuff...try using a lower octane fuel.
That is.....if the problem is a clogged injector.

 

[arnoldv]

Originally posted by SanDiegoExplr
are you running a v6 or a v8? Ive heard people say that its not good to run high octane gas in our v6's because it leaves more carbon behind and can mess up stuff...try using a lower octane fuel.
That is.....if the problem is a clogged injector.

It's a V6. I've only been using 91 octane for last 5 or 6 times I've pumped my gas. Could it be that bad for my car that it can mess up my car driving less than 600 miles? Thanks for the input!!

 

[SanDiegoExplr]

i believe that its possible. I mean, just think about the amount of gas thats gone through your car in 600 miles...5 or 6 times filling up is a lot of gas. I think thats your problem. Clean your injectors out and use a lower octane gas. That would be my reccomendation. Let me know how it goes!

 

[arnoldv]

I'll do that and I'll probably clean my MAF too.

 

[Texan01]

I run swamp gas in my cars (87) with no adverse effects. sounds like you need a complete tune up (new spark plugs, plug wires, air filter, grease the front suspension, change the oil, change the fuel filter, etc..)

I'd lay out some green on the basics first and then see what you get. The Navajo I think is very distinctive looking it's more aggressive looking than the Ex of that generation is.

My 95 has 106,000 on it and I've really only spent about $100 on it to do minor fixes.

 

[arnoldv]

Originally posted by SanDiegoExplr
i believe that its possible. I mean, just think about the amount of gas thats gone through your car in 600 miles...5 or 6 times filling up is a lot of gas. I think thats your problem. Clean your injectors out and use a lower octane gas. That would be my reccomendation. Let me know how it goes!

Chevron calls it "Techron". What's the point of putting "Techron" in their gasoline?

 

[williecume]

i dont want to upset anybody, but the higher the octane the slower/cleaner it burns when ignited.
therefore burning the mixture more thoroughly than with low octane.

low octane burns quicker which means there will be more air/fuel mixture left over because what doesnt burn turns into carbon which builds up anywhere it can.

but as JDraper said since there is a computer in your vehicle doesnt mean you have to use high octane. check the user manual (if you have it) that will tell you which octane level the truck requires. but the octane you use is totally up to you.

i personally use high octane to help keep carbon from building up. just so you know i have NOT noticed in increase in power, i have noticed a little increase in mileage. but i use it to help reduce carbon buildup.