Year of Manufacture *: 2003 Engine Code or Type *: 1.4 I-DSI ( Optional ) Scanner used: Carmanscan
I am running out of ideas with this - can anyone offer any advice on what to check next?
The car holds back at light throttle while trying to keep a steady speed, occasionally bringing up fault codes for misfire on all 4 cylinders. I think this is caused by a weak spark or a weak fuel mixture. The plugs have been changed and it is difficult to check plug Kvs with the scope as the COP coils have powerstage integrated. Driving at 50mph, at 3000 revs in 4th gear, the fault is quite pronounced and at that point the fuel trim is still correct and the llambda sensor it still switching. The fault can't be reproduced in the workshop. I have read that the EGR valve is a very common failure so I have blanked it off but there was no change. Feedback from the EGR valve can be seen in live data but I have no way of tell if it's correct. The manifold vacuum seems incorrect at idle, at 250mb. However at idle, again the fuel trim is bang on. I've read some interesting stuff about this engine which runs a higher than normal compression ratio with two spark plugs per cylinder to combat pre-ignition. I have found some corrosion in the 4 rear coils and wondered if a weak spark on the rear 4 plugs would cause this fault. However the coils are £80 each and I am reluctant to change them if there is no definite link. I would like to fix this as I have seen this fault on other cars, usually MAP sensor controlled, and find them very hard to pinpoint. Can anyone one help?
Re: Honda Jazz 1.4 I-DSI Light throttle misfire/hesitation
The question that must be asked is have you adjusted the valve clearances,especially as your idle vacuum reading is suspect.It has to be done on this engine,but it's quite a job (remove manifold etc.)so often not done at services.
Re: Honda Jazz 1.4 I-DSI Light throttle misfire/hesitation
I am not familiar with this vehicle but my gut feeling is that this is a fuelling problem and not ignition related. I would be interested to see the 4 gas readings at idle and fast idle which will give you a clue because I feel it is too lean and careful attention should be paid to the MAP Sensor. My Vacuum gauge reads in "hg so your reading in mb means nothing to me but would be interested to see what the conversion is. Best of luck
Pete M
Re: Honda Jazz 1.4 I-DSI Light throttle misfire/hesitation
I didn't know it had adjustable tappits, but sure enough it turns out that they should be checked every 25000 miles. I'll take a look.
Peter I think 250mb equals 22.5inhg which seems like a good manifold vacuum, maybe too good! Autodata pin out info says map sensor at idle 1.2 volts. Map sensor on this car is 0.85 volts at idle. I haven't tried it on the gas analyser, however short term and long term fuel trim at idle is perfect. I have a look at the gases. Thanks
Alan
Re: Honda Jazz 1.4 I-DSI Light throttle misfire/hesitation
If your valve clearances do check ok ,you might want to try and blank the egr port and then try driving the car to see if your drivability fault has cleared.Problems with these valves are common on this range ,i think it is a linear type similar to the vauxhall part.
Good luck
Dean
Re: Honda Jazz 1.4 I-DSI Light throttle misfire/hesitation
Hi all, I have told customer to take the car and come back if it gets a bit worse. I had spent too much time on it all ready. If it was not for the light coming on now and then they would not have bothered the hesitation is not that bad. I did blank the egr. also checked the valve clearances which took a bit of time as the manifold is over the rocker cover they were all ok. I cleaned up the coil connections that are common for water damage. Remove the coil extension boot and there is a spring that contacts the coil pin. The plugs are new and correct. The map is 21inhg at idle fuel trim is spot on at idle and when the hesitation is there at light throttle. The lambda looks good on the scope also. Did not scope ignition as i dont have a coil on plug pick up yet. I am going to try and capture some good live data from another car to compare if i can find one.
on August 22, 2009, 1:50 pm, in reply to "