Advice on minor issues please

BABOSS · 18-01-2006, 08:24 PM

Hi,

The following issues have presented themselves sice i replaced the head gasket:

1. When travelling on the freeway at a constant speed of 100km/h the car automatically decelerates than accelerates and keeps jolting the car very slightly. This is an interrmittant problem. This deceleration and jolting can be compared to when you're driving on the freeway fighting a strong headwind.

I have new NGK sparks and leads so i would think that maybe i need to replace the coil pack but i wan't to be sure that's the problem before i go puttin a new one in. First i thought maybe the timing is out, but then again it is a coil pack, so it should be ok. Also the TDC etc. was all done properly when the head gasket was replaced. There is no backfiring or spluttering.

2.The car before the head gasket replacement ran perfectly on petrol. Now if i switch from LPG to petrol the car stalls. When i cold start in petrol mode it starts for 2 secs then stalls, but runs perfectly on LPG except for issue no. 1. Maybe blocked injectors???

I thought i'd ask first to get a rough idea as i won't be able to get anyone dyno it untill next week.

Thanks for your replies.

gthofan · 18-01-2006, 08:30 PM

hey, when my head gasket went 2 months ago, this is the story:
the head gasket went, and had no power in petrol, there was nothing but spluttering.
on lpg it was fine. i had the head work done, but i had shocking problems with backfiring when the engine was under load, eg. accellerating out of a corner, with moderate to heavy accelleration. my mechanic changed the leads, distributor, coil, spark plugs. and a tune for petrol AND LPG (important) after all this it was fine!!
i had the stuttering at 100kmph aswell, untill i had the tuning done. now its perfect.
hope this helps a bit

18-01-2006, 09:37 PM

could be running lean

BABOSS · 18-01-2006, 09:43 PM

Is it common for the mixtures to change after replacing a head gasket? I would have thought it was electronically controlled. I've also tried resetting the ECU, no joy. Any chance of it being the coil pack itself?

gthofan · 18-01-2006, 09:47 PM

thats why the mixer for the lpg has to be altered during the lpg tune

gthofan · 18-01-2006, 09:49 PM

flasher ef, where in melb are you???

BABOSS · 18-01-2006, 09:51 PM

Narre Warren, 25min from Bayswater, 40-59min from the City.

gthofan · 18-01-2006, 09:54 PM

u should go to ausgas in bayswater and see steve, he has looked after me very well

BABOSS · 18-01-2006, 09:59 PM

Thanks mate but that's impractical for me if i took a taxi home, i have a good gas joint less than 1km away from me, but they are also flat out and won't help till next week or the week after, that's why i started this thread to listen to some suggestions of what the problems could be.

gthofan · 18-01-2006, 10:01 PM

ok, but the main thing will be an lpg tune, if uve changed the distributor, coil, leads, plugs etc already.
good luck mate

sphell · 18-01-2006, 10:21 PM

the surging on the fwy could be the oxy sensor. I had the same problem in the EA it had a very slight flat spot every now and again then. Changed oxy sensor and fixed it.

BABOSS · 19-01-2006, 03:21 AM

*UPDATE* It now runs on petrol and idles fine but as soon as i add any acceleration it putters and dies in park or drive. Hmmm.

CruizinEB · 19-01-2006, 03:23 AM

it could be the fuel filter ;)

gthofan · 19-01-2006, 07:37 AM

just ask snypereb (shaun) he had the same problem, and cost him a stack to get fixed. ended up needing a new computer

BABOSS · 20-01-2006, 12:49 AM

I don't think its anything major, definately not that bad to replace an ECU!

snypereb · 20-01-2006, 01:16 AM

Certainly did look at your cat convertor and your computer they are what went wrong in my car and it sounds like your car is doint exactly the same as mine i spent over $1200 finding this problem!!!

BABOSS · 20-01-2006, 01:23 AM

Snyper, it's MPFI so the ECU is different to yours and the 2.5" cat was only put in a month ago. This problem occured after i took apart my engine to replace the head gasket and put it all back together. It's not a major issue and as mentioned before it's likely to be running incorrect mixtures with possible fuel rail/ injector or filter problems, or the O2 sensor. The ECU is also fine.

snypereb · 20-01-2006, 01:26 AM

Sweet as mate i gather you did the head gasket yourself maybe do it again and check you have put everything back in the right place its not that bigger job is it!!!!

BABOSS · 20-01-2006, 02:51 AM

You've got to be ИИИИting me right? I don't wan't to; and shouldnt have to touch the motor for another 3-5 years. There is not much you can stuff up in a head gasket replacement, except when you have to align the timing marks, etc. but i had a mechanic help me with that bit before i put it back together. A lot of it is just plain mechanical common sense.