Please Help

rightio guys...

can someone PLEASE tell me wtf is goin on with my lude......ive taken it to like 3 different places and each place has given my a different answer... now im coming back to you guys for ur opinion and thoughts.

1988 lude, 2.0L Si, Auto
have replaced oxygen sensors and fuel filter - no difference
engine mods - 2.25 exhaust, extractors, POD
i have also had the timing belt done at 200,000ks
car has 203,000 on it now

ok heres the go:
real shit milage on full tank. around 250-280ks on a tank.

took it to 1st place - they sed exhaust valve on 2nd cylinder is leaking - was told that it will need replacing.

took it to honda - they sed that ECU was throwing a code - top dead centre sensor - they reset ECU and took it for test drive. once back there was no code. they sed that its fixed....

took it to 3rd place today - told them about what the other 2 places sed.. they sed they check it all out.
checked the timing - ok
checked fault codes - ok
check oxygen sensors - ok
compression test - 1/150, 2/180, 3/180, 4/190

as u could prob imagine.. im farking pissed off!!!

if anyone has any ideas, post it up!

-matt

0.5) Check your tire pressure, it should be 30-34PSI. More then that will show tiny gains of mileage, but less accelleration/braking grip, and possibly less turning grip depending on whether your sidewalls fold over with 32psi. Less then 30psi will give you less fuel mileage (a bit, sub 20 it goes downhill fast), make your cornering squishy, and give you slightly better grip on launches.
Thanks to Lebowski for reminding me about this.

1) Check for fuel leaks, it's easy to do, just smell around the fuel lines after you've driven somewhere. Smell fuel? You've got a leak. Leaks waste gas for one, and are a serious fire risk for two. My injector O-rings leak nicely, i need to do something about that.

2) Air filter, a dirty/clogged air filter can cause lousy mileage. It won't account for that much mileage, but it's a good place to start, and it's cheap.

3) Spark plugs. Worn spark plugs don't fire as effectively as new spark plugs. This manifests itself as reduced power, or missing. Both of which mean that you have to put your foot down further (and flow more fuel) for a given amount of acceleration. Plus, they are about $2 each for high quality NGK or Denso plugs. DO NOT use platinum, or iridium, the only benefit to platinum is that it lasts longer, it actually conducts more poorly then the stock plugs. Iridium plugs should only be used in a pure race motor (ala tonybaker, etc.), anything less then that and they won't have any effect except to last a loooong time (like, 120k+ miles). If you want to never replace your plugs again, use Iridium, but don't expect any power or mileage gains over stock NGK or Denso plugs. Sidenote: Do NOT use plugs made by anyone but NGK or (Nippon)Denso. Don't even touch Bosche or Autolite plugs, they may contaminate your hands and cause plug failure.

4) O2 sensor(s). As they wear out from old age, they produce less voltage. At lower voltage, the ECU thinks the engine is running lean, and richens it up. The end result is that the O2 sensor is telling the engine to run richer then it should. Eventually the sensor will die all together, and the check engine light will come on. I need to replace mine.

5) Intake air tempurature sensor. They occasionaly go bad, but rarely trip a check engine light. They have a direct and large affect on the air/fuel ratio, so one that is reading incorrectly can screw things up quite a bit. They are also pretty cheap from the wrecking yard, and probably pretty cheap from a parts store. I need to replace my IAT sensor too.

If you manage to get this far without fixing your mileage problem, something is more seriously wrong, possibilities include:

1) Partially clogged, or stuck open injectors. Clogged injectors don't flow enough fuel, which will throw off the O2 sensor, making it think that the entire engine is running lean when really only one cylinder is. The ECU then richens things up for the entire engine.

2) MAP sensor, usually combined with strange throttle response, or dead spots in the power band. Not cheap, fairly easy to get to (inside the black box of vacuum stuff). Difficulty update thanks to Kalm Traveler.

3) TPS, same as the MAP sensor symptom wise. Not cheap, fairly difficult, may require throttle body replacement.

4) Worn rings. They manifest themselves as reduced power (needing more throttle for a given amount of acceleration = less fuel mileage), oil burning, and lowered compression.

5) Burnt valve. Manifests itself as a flat spot while cranking(low compression on one cylinder), possibly a rough idle, and (maybe noticeably, maybe not) reduced power. Again, less power = more throttle needed = less mileage.

Run some fuel injection cleaner thru the system for a couple of fill ups. Might take 3-4 bottles. If that doesn't help pull the fuel rail off and look at the injectors to see if there are big partials in them. Clean as needed. Then replace the fuel filter. Pressure should be 40-45 psi at idle. Get a meter to check this.

Quote:

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Originally Posted by Richmond98

Check your tire pressure, it should be 30-34PSI. More then that will show tiny gains of mileage

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Tire pressure depends on the tire, where you are in sea level, metric/sae numbers and if that's measured hot or cold. There should be a set of numbers that tell you what to put the pressure at on the side of the tire. Might have a min/max or a hot/cold.

http://www.ozhonda.com/forum/showthread.php?t=30815

Also...next time title your thread properly please!

150 is a bit on the low side.

your broblem could be in the head, and they only solution is head rebuild.


did you replace both O2 sensors and are you down on power ???

as engines get older the throttle body gets clogged and dirty.. cleaners can do so much but there will always be build up that will get worse. This will affect idle cold idle, make your car shake a little run rougher..

most mechs over services will adjust the throttle to compensate for this.. this will include adjusting the little screw near the throttle body i think its called the cold idle adjustment or something.. basically lifts the idle slightly. It feels great driving but then affects your consumption. Yours is so old that chances are that it has been adjusted to max. The best way to fix that is to actually open the throttle body up and clean it out completely.

There is a possibility that this is your problem as its common amongst many cars.