Engine sluggish at low revs

[Fizz]

My sister has a 1999 Ford Laser 1.6, with 85,000km on the clock. Lately i've noticed that when accelerating, the car feels sluggish and hessitates a little when the revs are low (from idle to around 2500rpm). But once pass 3000rpm it suddenly picks up revs faster and runs like normal. Idling is stable and normal.

I've tried off-the-shelf injector and fuel system cleaners, but problem still persists. Serviced as normal, replaced spark plugs recently at 81,000km. Would appreciate some advise on possible problems. Thanks.

[Kiz_EG6]

...so are we talking bout ur car or ur sisters?!?

Have you considered the leads, not just the plugs.

Another option...sell it and buy a honda...problem solved :)

[dsp26]

There is a Ford Laser forums who posted a great write-up on a throttle body clean.. you should try it!!

the following was taken from another forum that uses the post from www.fordlaser.com



One common problem with most engines is carbon build up. Don't be mistaken IT SAPS POWER.

First, what is carbon and where does it come from?

Carbon is produced as a by-product of combustion. Fuel impurities and oil all get burnt during combustion, producing carbon. Carbon in itself is not the problem. It is very fine and powdered. The problem is when it mixes with oil vapor it becomes what is quite often referred to as "COKE". In this form it is exceptionally hard and unfortunately, over time builds on itself.

Where does it "gather"?

Hardened carbon deposits build up in the combustion chamber, the back of valve heads, in vacuum lines and ports and behind rings. I have re-built engines with less than 100,000 K's and found carbon deposits on the back of valves over 2mm thick. When you consider a valve only opens millimeters, this has a huge effect on flow. It also reduces compression as it can prevent the valve from fully closing. It can seize the rings in their piston lands and block the oil holes to the oil rings.

This can all be prevented/cured by performing a simple de-carb, using a can of carby cleaner. I find the CRC and Nulon carby cleaners to work very well. This should be carried out just prior to a oil filter and oil change.

HOW TO ON EFI CARS:

IMPORTANT NOTE. INTRODUCING CARBY CLEANER IN LARGE QUANTITIES INTO AN ENGINE WHILST IT IS OFF MAY RESULY IN HYDRAULIC LOCK OF THE CYLINDERS. THEY CAN FILL WITH FLUID AND THEN LOCK WHEN YOU TRY TO START THE CAR.

The process is quite simple. Get an aerosol can of carby cleaner with one of the small tube extensions. This will set you back from $10.00 to $20.00.

Start the car and bring it up to temperature. You may need a friend to "play the throttle" to prevent the engine from stalling. Alternately pick a suitable spacer (cardboard/plastic) and place it between the throttle stop and actuator on the throttle body to up the revs. With the car running (VERY IMPORTANT AS PER NOTE ABOVE) start with the PCV Valve on the cam cover. Unplug the hose at the PCV Valve, leaving the valve in place on the cam cover. Hold your finger over the end of the hose to prevent the "un-metered" air from stalling the engine. Squirt the carby cleaner into the hose in short bursts, say 2 to 3 seconds at a time with a second or two in-between squirts. Use about 1 third of the can. Now do the same for all other vacuum hoses going to the Inlet Manifold. In particular the hoses that provide vacuum advance to the distributor. Let the car run for a few minutes. Turn the engine off and leave the car for a few hours. Repeat the process, using any remaining carby cleaner. Take the car for a drive. Don't give it a hard time. Just a nice open run. Leave the car over night. Next day, bring the engine up to temperature and then change the oil and oil filter.

You will be surprised at what a difference this will make.

There is no need to do a de-carb every oil change, however it will clean out the inlet manifold.

The process is much the same for carby engines, however it is best to also remove the air filter and squirt carby cleaner directly into the carby. Don't forget to clean the vacuum lines. They do block up over time.
_________________

Don't worry, you can't screw anything up so long as you do it with the engine running and use one of the aerosol cans. Using the aerosol can as opposed to vacuum/venturi fed from a tin means you cant flood the cylinders. The worst thing that can happen is the engine will stall if you squirt in to much at a time, as you reduce the eficiency of the combustion cycle.

The other great advantage with a de-carb is it gets into the oil and will break down carbon deposits in Hydraulic lash adjusters (lifters) which will in turn make the lifters work better reducing HLA tick. This is why it is recomended that you perform an oil and oil filter change after the de-carb is complete.

The easiest place to start is with the posittive Crank Ventilation Valve on the cam cover. It is the small plastic piece which is on the top of the cam cover with the 1/4" ish rubber pipe which leads back to the inlet manafold. You simply pull the tube off of the PCV valve and squirt the carby cleaner into the tube past your thumb/finger. The PCV valve contains a small plunger which only allows pressure to be release from the cam cover. It wont suck in unless it is blocked.

* It really does help if you have two people.

Give it a go, I'm sure you will be happy with the results.

[dsp26]

BUT.. whatever you do, DO NOT USE THE STRAW!!!!!!!

mine got sucked into the plenum.. pain in the arse to get out having a high power vacuum at TB end (with TB off) and and an air compressor blowing through each sparkplug hole one at a time.. you have to crank the engine bit by bit until the intake valve opens....

[Fizz]

...so are we talking bout ur car or ur sisters?!?

Have you considered the leads, not just the plugs.

Another option...sell it and buy a honda...problem solved :)

LoL...its me sister's car. Sorry for the confusion.

[lil_miss_vtec]

I had a 1992 mazda astina - very similar to the laser... & it had the same problem.... I did what it said in the post about carby cleaner (although it was injected) & it worked great.... my car had 230,000kms on it so it had to be done regularly, my dad bought it off me 3yrs ago since then & it still runs fine now! :D

[Fizz]

BUT.. whatever you do, DO NOT USE THE STRAW!!!!!!!

mine got sucked into the plenum.. pain in the arse to get out having a high power vacuum at TB end (with TB off) and and an air compressor blowing through each sparkplug hole one at a time.. you have to crank the engine bit by bit until the intake valve opens....


Thanks for that link. If its got carbon build-up, is it possible to have this problem only occur in the low revs but perfectly fine in higher revs?

Could this problem be related to the timing belt? Possible or highly unlikely?

[lil_miss_vtec]

i'd say unlikely.....??

[Fizz]

yeah probably unlikely i guess. i thought about the plug leads too but if it was that the engine would have same problems in higher revs too. This problem only occurs below 3000rpm.

Just checked the logbooks, and noticed that the fuel filter was never replaced. Would this have an impact of the current problems?

[lil_miss_vtec]

sure would.... give it a full service, oil, oil filer, plugs & leads (if they r worn)
get some carby/injector cleaner...

doubt its ur timing belt lol

maybe shitty fuel?

All I know is when I've had problems like this & I havnt changed the filters for awhile I just go thru & change them, trying to eliminate the problem

I'd say its ur injectors or something... try putting some injector cleaner in ur fuel or taking it to a mechanic who can clean them... preferably off the car

hope it helps!!

[Limbo]

wear and tear, clean the throttle and do a service on it

[Phuong1987]

Check ur IAT sensor
Read the Symptoms
http://www.ozhonda.com/forum/showthread.php?t=67515

[dsp26]

Check ur IAT sensor
Read the Symptoms
http://www.ozhonda.com/forum/showthread.php?t=67515

??? It aint'a a Honda dude....

[BluEG]

haha, yeah try carby and throttle cleaner, could be carbon
build up on the tps sensor!

if not get the timing checked out.

[Phuong1987]

??? It aint'a a Honda dude....

yeh i know its not a honda but it has the same symptom

[Fizz]

thanks for all the replies guys. over the weekend i've changed the oil, oil filter, air filter and checked the plugs but still showing the same symptoms. so i've booked it in for a carbon clean this week...hope that should fix it.

[b01ng]

try tightening the timing, my eg5 was running like that aswell, but was all good after the timing was tightened

[Fizz]

try tightening the timing, my eg5 was running like that aswell, but was all good after the timing was tightened

sorry but how do i tighten the timing? is this an easy task or should it only be carried out by a mechanic?

anyways i had a couple of quotes for carbon cleaning/injector cleaning + replace fuel filter, and the prices are about the $200 mark.

[Phuong1987]

does it go away after a while, or it happens all the time while driving under 3500rpm?

[Fizz]

does it go away after a while, or it happens all the time while driving under 3500rpm?

pretty much all the time when below 3000rpm. it feels like there is loss of power (like a little hiccup) when you begin accelerating from idle to 3000rpm....but most noticable around 2000-2500rpm.

[Fizz]

hi guys, update: sent the car for a check at UltraTune. diagnosis was that the injectors are fine but the car has a faulty air flow meter? anyways was quoted $390 supplied and fitted for a new unit :eek:

[b01ng]

there is like a black rubber blanking plug in timing belt shield, about half
way between the cam & the crank pulleys, near the back.
take the plug out and you will see the timing bolt,you can get a socket wrench from here, just loosen it, then re-tighten