Well, My 93 Alty has been getting very poor mileage for the past year or so. I get about 90M ( 200km) after I put in $20 (Cnd).
The first thing I did was a tuneup, plugs, caps, rotors. And then after some 'investigation' I bought and installed O2 and coolant temp sensors. Still, nothing worked.
After that I finally brought my car into two different shops, the last being a Nissan dealership, and both could not find anything wrong. ( I'm assuming they used the OBD..........).
Anyway, still doing my own 'investigating', I brought my car in to get the fuel injector cleaned. Ta-dah, I noticed the first and only improvment. But It's back to it's old self. What do I do now?
p.s. the car idles and runs perfectly with 240,000 km.
Poor Fuel Economy
possible intake gasket leak at number 4 cyl. very common for them to get sucked in there. The only problem with that is you say it idles ok. typically when that gets sucked in enough the car has a very rough idle or high idle. Its possible you may be at the point where it is only pulled in so far. There is a very simple test to check this but it requires the use of a consult II unit(factory scan tool) or equivalant DSO(Digital Storage Oscilliscope) While monitering the O2 in data moniter in line graph mode watch the pattern if its sucking air it will lock on 0v if you sray carb clean ,brake clean, or use a propane enrichment bottle near the bottom of the #4 intake runner the graph will spike rich. It is an almost imediate reaction to the enrichment device. If you have a little dough to invest in researching this take it to the dealer and ask them if they will try this for you with their consultII. they will need to know where to go with the consult though so here it is.
Engine>>>Engine>>>>Data moniter>>>>Selection from menu>>>>>Line Graph>>>>O2>>>Start.
Engine>>>Engine>>>>Data moniter>>>>Selection from menu>>>>>Line Graph>>>>O2>>>Start.
Ok, I was thinking something like bad injectors, or stuck open injectors. Is that possible? That's why I figure the fuel injection cleaning increased my mileage......?
But anyway,..... Are there any symtoms to intake gasket leaks? Is it worth it to try to diagnose it first at the dealer, or just get them to change the gasket. (how much?)
But anyway,..... Are there any symtoms to intake gasket leaks? Is it worth it to try to diagnose it first at the dealer, or just get them to change the gasket. (how much?)
price depends on area of the country. its better to have them be sure first. cause the job is like 5 to 8 hrs flat rate time. that can be pretty pricey alone especially if thats not your problem.
You could very well have a bad injector. but the graph mode on the o2 will show that as well but be rich all the time.
they will charge you about an hours labor to perform those checks. At my dealer the rate is $95 an hour. but this area is kinda high.
You could very well have a bad injector. but the graph mode on the o2 will show that as well but be rich all the time.
they will charge you about an hours labor to perform those checks. At my dealer the rate is $95 an hour. but this area is kinda high.