Mechanics

ROUGH IDLE IN DRIVE, DECREASED FUEL ECONOMY

2004 Honda Jazz • 80,000 miles

Our Honda Jazz (vtec, auto) has been at the mechanics every couple of months for the last year with this same problem. When the engine is cold, it idles rough and almost stalls, only when in drive (park, reverse and neutral are fine). When slowing down, close to 1000RPM's, the engine splutters and again almost stalls. Sometimes when taking the foot off the accelerator the car runs smoothly for a bit and then******, almost like it's suddenly switching to a lower gear suddenly. Accelerating, the engine runs fine. We have had the flywheel replaced (no improvement) and have had the valves cleaned (no improvement). After numerous trips to Honda, they keep giving it back with no improvement. When the idling is very bad we also notice the fuel economy drop to less that 9Km/ltr (at the best of times it's not better than 11km/ltr). So we're not sure if it's because of this problem. Any advice would be appreciated
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Johden
September 5, 2011.




YAY! Thankyou so much for your help! We picked up the car and it's PERFECT! No rough idle, no feeling like it's going to stall, no sticky brakes and the car feels like new! Strangely, when we took the car in on Monday, the car was running beautifully, with no hint of feeling like it was going to stall, even though on Fri-Sun it was still idling quite roughly. I don't know if it takes time after cleaning the valves for things to "clear through" or did something just "fix itself"? Either way, when we picked it up after the service, the mechanic did say that they had rechecked everything and readjusted the valves and O2 sensors. We did not get to speak to the manager again to find out what exactly was the problem, as he had already left by the time picked up the car, but are very grateful that it is running beautifully now. Now we're seeing if the fuel economy improves. We filled up as soon as we got the car back and so far we've done over 130kms and the fuel needle has barely dropped (previously it would've dropped about 20% already). So fingers crossed.
Again we want to thankyou from the bottom of our hearts for your advice. Thankyou!

Tiny
Johden
Sep 15, 2011.
Glad to hear the good news.

Have a great day.

KHLow2008
Sep 15, 2011.
Hi Johden,

did you find out what they did to fix the problem. I have the exact same problem. PLease HELP !

What was the exact cause of the problem

Tiny
Burner_18
Aug 4, 2012.
We had the whole thing re calibrated, cleaned out, re-tuned. But about 4 weeks later the problem came back and the fuel economy dropped back to what it used to be again. We did take it back and the mechanic basically said they couldn't understand what was going on. They suggested we replace the entire gear box next which was going to cost a bomb. Because of all the troubles we had with this car, we decided to just get rid of it and get a new one. It ended up being cheaper to trade it in and buy a brand new car than replace the entire gear box! Sorry to hear you've got the same problem. One person did mention to us that that this particular model needed a specific type of engine oil that only Honda produces. Any other type of oil wrecks the engine. I have no idea how true this is, but you may want to look into it? Hope you can get to the bottom of it. We weren't able to

Tiny
Johden
Aug 5, 2012.
I had almost forgotten about this and lately I had the chance to do a diagnostic on a vehicle with similar symptoms.

O2 sensors etc and many other components were tested but finally the part that made a chage was the EGR system which showed no trouble codes. Replacement of the EGR valve (used part, twice)and cleaning the ports did not solve the problem of the rough idle and struggling at low speed, within the range of 1000 to 2000 rpm.

Disconnecting the EGR solenoid wire connector stopped all the problems and after that the vehicle was taken back by the customer as he had to go out state so I did not have the chance to rectify the problem. When the vehicle left it was with the EGR not connected and customer did not call back to say anything so I don't know how it goes.

From above, I gather it is the EGR system that is causing the problem and could be a PCM fault.

KHLow2008
Aug 5, 2012.
Thanks for your advice Johden,
Its unfortunate that you had to trade your car and we really didnt get a definitive solution.

KHLow2008,
Explain Disconnecting EGR solenoid wire connector?
I have changed the EGR valve.

Tiny
Burner_18
Aug 5, 2012.
At the EGR valve, unplug the connector and retest.

KHLow2008
Aug 5, 2012.
Ok, I will try that tomorrow, although I think I have already.

My problem is that when the car is cold and I drive out and stop/idle in traffic the engine vibrates violently. Its worse when the a/c is on. Funny thing is that when the car is really warmed up, it will smooth right out. Since recently it has gotten worse though.
I have so far changed EGR, TPS, IAC, throttle body, o2 sensor, air temp sensor, Coolant temperature sensor and Tried another map sensor, catalyic converter replaced, I have changed air filter, gas filter, honda ngk plugs, honda oil and oil filter, honda CVT Transmission oil. I have also changed all 8 coil packs.
I think thats everything that has been replaced. Not sure where else to look at this point.

Tiny
Burner_18
Aug 5, 2012.
Were the valve clearances checked?
You might need to have the PCM updated if it does not have the latest software. That would mean a visit to the dealer.
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KHLow2008
Aug 5, 2012.

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