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Hello. I am having difficulty achieving good gas mileage and have a bit of hesitation on acceleration.I have checked the following: fuel pressure okay, new iridium plugs, new cap and rotor, correct coil resistance, shift and lockup solenoids function, new egr, new fuel filter, clean air filter, correct voltage on tps (has not been tested with Digital oscilliscope), new denso o2 sensors. My goal is to improve my acceleration to its optimal state, and improve my mileage. I have noticed a little extra carbon on the exhaust tip too.
Any help would be great. thanks.
1997 Accord SE 4dr Auto 2.2L 180k miles.
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Have you ever opened up and cleaned the EGR ports? (see the post in the DIY section for EXACT instructions on how to do it and what I'm talking about) that can cause hesitation. Also, my new favorite thing, run a can of seafoam through the motor, and a can through the fuel just to get everything cleaned up.
To tell the truth, that was one of the first things i checked into, but forgot to list. originally they were terribly plugged and that was an instant improvement. but they are clear now. The EGR valve is a couple months old, and actually improved my mileage a little bit.
The transmission fluid has been flushed out with honda fluid and a little bit of lucas trans slip.
The wires have not been changed, however they have specified resistance for each given length.
The hesitation is less noticeable with the A/C turned on. Shifts seem a little more firm with a/c on. Does the computer rich the fuel mixture when the A/C is running?
From a dead stop, if you apply the gas pedal, it hesitates. if you press WOT, or barely apply gas pedal it feels like it hesitates until you lower the pedal into a certain position, then it accelerates pretty good. After first and maybe 2nd gear, it requires a lot of pressure to shift up, otherwise it takes its sweet time to go into gear.
There is not any exhaust backpressure.
I havent fixed upper seals and a little bit of oil still seaps into the plug wire space.
Anyone 2nd checking the TPS on a digital oscilliscope?
Perhaps the ignition such as coil is weak? maybe alternator not putting enough out?
Check fuel pressure regulator vacuum reference line. A distinct smell of gasoline would indicate a ruptured diaphragm. This allows fuel to be pulled directly into intake manifold and will reduce gas mileage.
Check Long Term Fuel Trim. A significant movement +/- might suggest an O2 sensor problem, fuel pressure problem, injector problem, etc(how did you check fuel pressure? was in spec?).
Many suspect TPS problem, but I've never read of a documented case where that was the problem. You can check TPS voltage (ground referenced) on red/blk wire from TPS w/ a VOM. It should be 0.5V at idle stop and 4.5V at full throttle and smoothly transition between those positions. A wire splice installed on the red/blk wire is easiest way to check.
Check base timing. Check brakes front and rear for excessive drag. Unusual tire wear could indicate severe misalignment.
Check engine compressions w/ warm engine, WOT, and at least 4 compression strokes on each cylinder. Compressions should be 135-178 psi or more. Max variation between cylinders is 28 psig.
See you down the ROW
1994 Accord EX
2003 Acura MDX
2006 Acura TSX
I checked the fuel regulator vacuum line, it smells a little bit like gas, but the tube does not seem like it is saturated or wet inside. I know the alignment is off some. Sometimes i am able to notice when i accelerate sometimes it sounds like in the process someplace in first gear it sounds like it accelerates in 3 stages like 3 distinct sounds, then smoothly accelerates. As for the TPS i am still unsure without using a DSO, because on multimeter and scantool the values are fairly slow and look right. Is it normal for the scantool to show the tps at a % higher than 0 when your not touching the throttle?. I havent got a hold of a mastertech to check the fuel trim yet lately. What circumstances am i looking for change in fuel trim, e.g. time period? That I know, the fuel pressure is in spec, however i cannot remember whether I tested the regulator more than pinching the vacuum line. To check the pressure, i recall removing fuel filter banjo bolt, and installing a specific adapter to hook it up to the gauge. The reading was 35psi at idle, and at the time it maintained pressure after snapping the throttle. The most ever did with the regulator would be to pinch vacuum line. As for the compression test, results are as following:
with all plugs out:
1st puff/final reading
I think your compressions are OK. I've never tried a "running engine compression" and don't know what to make of them. The compression gauge has a check valve which captures the highest pressure, so not sure why they are lower.
Fuel pressure w/ vacuum line attached should be lower (31-38 psi) than w/o the vacuum line attached (38-46). If you definitely smell gas, a new fuel pressure regulator is indicated. Fuel will evaporate rapidly in the vacuum line, so not surprising to find no liquid gas. Run engine w/ vacuum line disconnected and feelfor gasoline leaking from the vacuum reference fitting on the regulator. W/ a ruptured diaphragm there should be a steady gas flow.
See you down the ROW
1994 Accord EX
2003 Acura MDX
2006 Acura TSX
The resolution sounded too good to be true. I took the vacuum hose off the regulator and didnt notice anything. the more i think about it though, with the a/c on, a lot of times, i hold the throttle down a little bit on acceleration, and there seems to be a delay of 5 seconds or so before it starts to accelerate. Any signs that this might be the transmission? It did have ugly looking fluid when i got it but its driven more less the same since I flushed it a couple years ago. What should i check into next?
I have a question about my map sensor in regards to the situation. I was just testing it today with a multimeter. With the car off key on, i have no signal. However, I get a pretty accurate reading with the car on, up to 2 volts, then i dont see it go past 2.1 . Looking off the chart,if it is not reading 0 vacuum as close to 2.9 volts, and reading no voltage, doesnt the computer see it as having more vacuum even though its reading the TPS, but the tps might be messed up too i guess. Any ideas on this subject matter?
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