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Hesitation on acceleration
Posted: September 12th, 2010, 11:22 am
by stumsport
Hi, I need some help. I own a 1996 MX3 1.8 V6 and my problem is this. When I accelerate, the car is very hesitant, like it is struggling to get fuel or misfiring. Once I get past 3500rpm it seems to run better but if I accelerate hard again it seems to misfire again and is struggling to accelerate. When the car is idling it seems to misfire, if I press the accelerator and get it above 3500rpm it seems to run ok. I have tried disconnecting the IAC valve but all that does is make the rpm's drop to about 400rpm and doesn't solve the problem. I haven't tried anything with the BAC valve yet. The car has had a new distributor and leads so doesn't seem to be that. Any idea's that could help would be great.
Regards
Stumsport
Re: Hesitation on acceleration
Posted: September 12th, 2010, 6:38 pm
by TMP39
sounds like same issue my buddy had with his honda. a little integra with b16 sawp. but anyways what gas are you using. difference between 87 and 91 would make a difference since 91 takes longer to burn
but anyways depending on what gas your using try playing with your timing a bit. advance it 2 degrees and if its worse retard it. but it could also be a low vacuum issue, there always fun
Re: Hesitation on acceleration
Posted: September 13th, 2010, 12:03 am
by _-Night-Shade-_
87 does not burn faster than 91. Octane number has nothing to do with how the fuel is combusted. Octane number is just the fuel's ability to resist predetonation.
Re: Hesitation on acceleration
Posted: September 13th, 2010, 9:51 am
by stumsport
Using regular unleaded petrol at the moment but will give super unleaded a try it carn't hurt. I will also have a look at the timing aswell and see if that makes a difference. As for the vacum I wouldn't know were to start do you have any ideas.
Cheers
stumsport
Re: Hesitation on acceleration
Posted: September 13th, 2010, 11:02 am
by mazdags94
Do you have the stock accordian style intake tubing? If so, check for cracks in between the little creases. That could be causing it (thus, vac leak).
Re: Hesitation on acceleration
Posted: September 13th, 2010, 2:37 pm
by stumsport
When you say intake tubeing do you mean leading away from the air filter box sorry for being numb.
Cheers
stumsport
Re: Hesitation on acceleration
Posted: September 13th, 2010, 9:45 pm
by TMP39
actually 87 and 91 octane do burn differently 87 burns faster and 91 burns slower. octane has nothing to do with prdetination. predetination happens cause its either to hot and your timings off.
Re: Hesitation on acceleration
Posted: September 14th, 2010, 12:23 am
by _-Night-Shade-_
TMP39 wrote:actually 87 and 91 octane do burn differently 87 burns faster and 91 burns slower. octane has nothing to do with prdetination. predetination happens cause its either to hot and your timings off.
I'm worried about you man...
http://en.wikipedia.org/wiki/Octane_number" onclick="window.open(this.href);return false;
The octane rating is a measure of the resistance of petrol and other fuels to autoignition in spark-ignition internal combustion engines.
...
Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner.
...
A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
Why is there so much misinformation floating around on the forum lately? People need to get their facts right before they say stuff.
Re: Hesitation on acceleration
Posted: September 14th, 2010, 9:08 am
by Ryan
No offence, but Wiki is a bad reference, especially when you're concerned about misinformation.
Not saying you're wrong...
http://auto.howstuffworks.com/fuel-effi ... tion90.htm" onclick="window.open(this.href);return false;
Re: Hesitation on acceleration
Posted: September 14th, 2010, 12:31 pm
by _-Night-Shade-_
You know what, everyone keeps hating on Wiki but it's an award-winning encyclopedia and everything is reviewed when somebody alters an article. I usually do more indepth searches when I'm trying to find out more about something and there has never been anything that conflicted with the information on Wiki. If you truly don't believe it, it lists all of its references at the bottom of the page so you know it's not BS.
Re: Hesitation on acceleration
Posted: September 14th, 2010, 12:55 pm
by h3xt0r
Night Shade...
1.) You have the same number of posts right now as the year I was born... COOL!
2.) Totally agree. If you don't know if Wiki is full of crap or not just check the references down below.
In regards to Hesitation. Had a similar problem in the same power band as you. I did three things to fix it.
1.) Advance/Retard timing
2.) Replaced Spark plugs and wires
3.) Replaced air filter and fuel filter.
Thats What I did to fix mine. My guess, probably be the spark plugs and wires and/or the timing as TNP39 stated. I'd check the spark plugs first personal just because its alot easier to get to than the timing.
Re: Hesitation on acceleration
Posted: September 14th, 2010, 3:15 pm
by mazdags94
how many miles on the engine and when was your last tune up? Lets start there....
You replaced the disty but is it new or used? How many miles did you put on it.
Re: Hesitation on acceleration
Posted: September 14th, 2010, 4:24 pm
by stumsport
Thanks for all the info lads and lasses ( if any ).
Disty is new as are the leads will check the plugs but sure they are new aswell. To be honest I haven't had the car long and bought it with this problem and as you might have guessed its my first MX3, only done 300 miles in it. Last service ( tune up ) was about 4 months ago according to the guy I bought the car off don't know how reliable that info is tho. Will give the timing and the filters a go and see if that sort's it. Will also give the petrol a go see if it runs a bit better on a tank of the good stuff.
Cheers
stumsport
Re: Hesitation on acceleration
Posted: September 14th, 2010, 6:59 pm
by davmac
This problem is often electrical (wires, plugs, etc) but since you have new parts my first thought is plugged exhaust - usually catalytic converter. You can disconnect the exhaust in front of the converter and see if this fixes the problem. Your car will be loud but no hesitation if that is the problem.
Re: Hesitation on acceleration
Posted: September 15th, 2010, 4:18 am
by _-Night-Shade-_
h3xt0r wrote:Night Shade...
1.) You have the same number of posts right now as the year I was born... COOL!
2.) Totally agree. If you don't know if Wiki is full of crap or not just check the references down below.
In regards to Hesitation. Had a similar problem in the same power band as you. I did three things to fix it.
1.) Advance/Retard timing
2.) Replaced Spark plugs and wires
3.) Replaced air filter and fuel filter.
Thats What I did to fix mine. My guess, probably be the spark plugs and wires and/or the timing as TNP39 stated. I'd check the spark plugs first personal just because its alot easier to get to than the timing.
You're 1990? Me too! ;D