Mivec 4G93 - feeling of impact (hesitate/sag) when decelerating. PLS HELP!!

[.:JiT_187:.]

My mivec have the feeling of impact (hesitate/sag) when decelerating
(when rpm drop till around 1300-1000 ),
If I engage the clutch or accelerate, it's ok.
especially at 1st gear, feel like someone bang me for behind

did anyone having this problem before?
PLS HELP!!

TQ

 

[Izso]

you mean it jerks very violently forward when decelerating?

 

[vr2turbo]

Decelerate in 1st gear??

 

[g88]

My mivec have the feeling of impact (hesitate/sag) when decelerating
(when rpm drop till around 1300-1000 ),
If I engage the clutch or accelerate, it's ok.
especially at 1st gear, feel like someone bang me for behind

did anyone having this problem before?
PLS HELP!!

TQ

Can you provide how your 'rojak' work ? e.g detail modification or mix match of engine, piston, manifold, gearbox, ecu, wiring etc....

 

[.:JiT_187:.]

you mean it jerks very violently forward when decelerating?

yes..it has a feeling of violently forward when rpm drop till around 1300

---------- Post added at 08:33 AM ---------- 6 hour anti-bump limit - Previous post was at 08:29 AM ----------

Decelerate in 1st gear??

yup..when traffic jam or wanna slow down
decelerate and rpm drop till around 1300 it happen
1st gear is more obvious

---------- Post added at 08:38 AM ---------- 6 hour anti-bump limit - Previous post was at 08:33 AM ----------

Can you provide how your 'rojak' work ? e.g detail modification or mix match of engine, piston, manifold, gearbox, ecu, wiring etc....

4g93 block, open pod air filter, 2.3" piping, s flow exhaust

others all stock 4g92 mivec

this problem happened also before i change 4g93 block

 

[vr2turbo]

yup..when traffic jam or wanna slow down
decelerate and rpm drop till around 1300 it happen
1st gear is more obvious

Not sure what you mean? When decelerating how you manage to put into 1st gear?
Unless you mean accelerating??

 

[.:JiT_187:.]

Not sure what you mean? When decelerating how you manage to put into 1st gear?
Unless you mean accelerating??

Like release the gas padel while driving (with gear engage), when rpm drop till around 1300, feel a impact.
At 1st gear is most obvious (bang harder)

 

[Izso]

Sounds like cluth kick. Haha! It sounds like a problem with the clutch, like when you don't control the clutch properly and it suddenly bites. I dunno man. Maybe Mivec has something special that other GB don't have

 

[vr2turbo]

Sounds like cluth kick. Haha! It sounds like a problem with the clutch, like when you don't control the clutch properly and it suddenly bites. I dunno man. Maybe Mivec has something special that other GB don't have

Mivec actually nothing special
MIVEC is (Mitsubishi Innovative Valve timing Electronic Control system) is the brand name of a variable valve timing (VVT) engine technology developed by Mitsubishi Motors. Different manufacturer name theirs differently ...

---------- Post added at 07:27 AM ---------- 6 hour anti-bump limit - Previous post was at 07:22 AM ----------

Like release the gas padel while driving (with gear engage), when rpm drop till around 1300, feel a impact.
At 1st gear is most obvious (bang harder)

In that case I suspect fuel feed problem since you mentioned acceleration time is no problem. When decelerate fuel should be cut so that engine slows down. If fuel still going in then cut at inconsistent rate then the feeling of the jerk.
If you step on the pedal then release then step on the pedal then release again continuously you will get the same effect, right?

 

[Izso]

Fueling! Good point. Perhaps it's a simple matter of changing the fuel filter since Mivecs are ancient.

 

[vr2turbo]

Fueling! Good point. Perhaps it's a simple matter of changing the fuel filter since Mivecs are ancient.

Oh yah! could be clogged fuel filter also.....hahaha

 

[^pomen_GTR^]

nahhhhh.. first of all...after that rojak mod...what kind of brain the engine has?

stock mivec ecu?? sure it wont run perfectly since the engine displacement higher and dynamic different needs different mapping to suits...


solve that first and u should be good to go

 

[.:JiT_187:.]

Mivec actually nothing special
MIVEC is (Mitsubishi Innovative Valve timing Electronic Control system) is the brand name of a variable valve timing (VVT) engine technology developed by Mitsubishi Motors. Different manufacturer name theirs differently ...

---------- Post added at 07:27 AM ---------- 6 hour anti-bump limit - Previous post was at 07:22 AM ----------



In that case I suspect fuel feed problem since you mentioned acceleration time is no problem. When decelerate fuel should be cut so that engine slows down. If fuel still going in then cut at inconsistent rate then the feeling of the jerk.
If you step on the pedal then release then step on the pedal then release again continuously you will get the same effect, right?

U r right

---------- Post added at 05:29 PM ---------- 6 hour anti-bump limit - Previous post was at 05:27 PM ----------

Fueling! Good point. Perhaps it's a simple matter of changing the fuel filter since Mivecs are ancient.

Oh yah! could be clogged fuel filter also.....hahaha

I changed fuel filter since 1.5 years back
After change still the same, only more serious recently

---------- Post added at 05:32 PM ---------- 6 hour anti-bump limit - Previous post was at 05:29 PM ----------

nahhhhh.. first of all...after that rojak mod...what kind of brain the engine has?

stock mivec ecu?? sure it wont run perfectly since the engine displacement higher and dynamic different needs different mapping to suits...


solve that first and u should be good to go

I have this problem also before change the block
Before it was stock Mivec 1.6
only open pod air filter, piping and exhaust changed

 

[Izso]

I think the best way to troubleshoot this is to experience it. We're guessing too much here.

Oh and there's still the possibility of fueling issues, specifically the fuel pump or injectors.

 

[vr2turbo]

Agree, have to trouble shoot one by one since TS seems to have done some of our suggestions already and ours mostly guess work....

 

[.:JiT_187:.]

I think the best way to troubleshoot this is to experience it. We're guessing too much here.

Oh and there's still the possibility of fueling issues, specifically the fuel pump or injectors.

Agree, have to trouble shoot one by one since TS seems to have done some of our suggestions already and ours mostly guess work....

How can I check both condition?
Or need to replace it and test?

 

[^pomen_GTR^]

reset TPS position already yet/ (or recalibrate the tps reading first)

 

[.:JiT_187:.]

reset TPS position already yet/ (or recalibrate the tps reading first)

The tps is 0.5v when throtle body close…is it correct?
How to reset/calibrate the tps?

 

[kayour]

The tps is 0.5v when throtle body close…is it correct?
How to reset/calibrate the tps?

loosen the tps screw...then adjust it...cw/ ccw... to 05-0.6-0.7v...dun remember la
but from my experience...the problem when u touch the tps is when acccelarating 1000-1500 rpm
got jerking between that
then after calibrate tps...ok la

 

[.:JiT_187:.]

loosen the tps screw...then adjust it...cw/ ccw... to 05-0.6-0.7v...dun remember la
but from my experience...the problem when u touch the tps is when acccelarating 1000-1500 rpm
got jerking between that
then after calibrate tps...ok la

0.5v is ok then right?
Should i need to calibrate again?