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Old 9th May 2006, 00:29   #1
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Default RPM Surges-Throttle Body Cleaning

Hey guys, another problem has started....!

The RPM goes up and down ( 800- 1000) at Idle speeds, The engine takes more RPM than speed when moving first gear..and on road whenever I speed up..the RPM reves more than the speed ( RPM goes 2000 and then comes down to 1500)..!
This happened a few months back and got resolved on its own...I was suspecting a dirty throttle since the engine is timed and tuned..! The dealer confirms my suspicion..However I wanted to know that...Till date I've never had to clean the Fuel Injectors...! Whenever I myself asked the Showroom Service Tech to do it, I was advised that they are fine and don't need cleaning...So should I take their advise or should I go ahead and do it anyway...!

Does a dirty throttle cause Surges in RPM...!
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Old 20th September 2006, 02:02   #2
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I have exactly the same damn problem in my Lancer, only to a lesser extent & during idle.

It surges erratically between 750 & 950RPM during idle. Also feels a bit sluggish during initial pickup, especially with the air-conditioning on. Should maybe get the throttle body & fuel rails removed & cleaned thoroughly, along with all sensors.

We've isolated part of the problem so far - it seems to be cylinder #2.

Any advice / inputs anyone?
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Old 20th September 2006, 22:29   #3
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Get your Idle Air Control valve checked that could be the culprit,

@ elf same thing applies to you first get that checked also how did you isolated problem to cylinder #2 ? have you checked compression on all four cylinders?
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Old 20th September 2006, 23:04   #4
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Hi,

Well the I got the problem rectified a long time back, here's what I did, I got the Air filter cleaned with the Air, Got the passage to the throttle cleaned same way, Now for throttle, I got that Rust off spray the workshop uses and it removed quite a lot of carbon, Din't get the body opened but the spray cleaned most of it, Lastly, I had the mech open the fuel Filter bolt and spurted the fuel out, which was black and after a few seconds clean fuel came through.
All these removed the surges and has enhanced pickup and response, I have also got the injectors checked by the workshop periodically , which are always found clean, No blockage ever...!
I simply use Power and Regular in a mixed combination...!
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Old 21st September 2006, 01:05   #5
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After posting on the forum last night, I did some extensive research on the web about fuel injection & ancilliary systems.

I've already had my K&N washed, cleaned & oiled, & my injectors are sparkling clean & atomising the fuel correctly. I use only Speed & have just finished my first tankfull of Power (which I find better).

It seems the problem might be with some slight clogging somewhere in the fuel rails, especially the one supplying gas to cylinder #2 which seems a bit undernourished.

Am going to get to my garage soon & have all fuel systems opened up - filter, throttle body, fuel rails, injectors, sensors & supply lines, & then have STP / Abro carb spray & compressed air liberally applied throughout. I guess this should clean up stuff. Shall also get my auto electrician to check & clean all sensors & attendant wiring.

Shall post results shortly after that. Any advice anyone?

If the problem isn't solved post that, shall run the compression check that FR advises (shall call / coordinate with you before any checks, F_R).

Thanks guys for the advice.

Ciao!

PS: Did your gas mileage improve post your cleanup, wolfinstein?

Last edited by elf : 21st September 2006 at 01:07.
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Old 21st September 2006, 21:03   #6
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Ya it improved a little, However the engine power and performance were the major improvements.
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Old 22nd September 2006, 08:18   #7
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I have almost a similar problem with my Accent. No matter how much I try to rev it does not move over 2500 RPM.

I was thinking of taking to a mechanic, but I wanted to be sure what I tell him instead of just telling him this much. I dont want unnecessary bills says that is gone this is gone hence you have to pay this much. You know what I mean.

Any solutions for this?
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Old 22nd September 2006, 11:57   #8
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well, I'm also very much like you in that case of having no unecessary expenditure,Your RPM does not go above 2500, Thats something which apprantely is different however its almost the same culprit, Clogged Fuel Filter, Fuel Injectors need cleaning, Air Filter's time for replacement and throttle body needs to opened and spray cleaned. This will cost a small amount but I'm sure it will help solve the problem for a long period of time, Generally throttles get dirty, due to dust and driving conditions, So its advised to get them cleaned at least once in two services.
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Old 22nd September 2006, 12:15   #9
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Quote:
Originally Posted by Ironmarine
I have almost a similar problem with my Accent. No matter how much I try to rev it does not move over 2500 RPM.

Any solutions for this?

Boss if what you say is true then you have a sensor failure somewhere which is causing the ECU to go into safe mode. Take it to an authorised service centre and get the car scanned. They should either do it for free or charge you Rs250 max.

Dont go to any road side garage. Since you are in Banglore why dont you show your car to Psycho.

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Old 22nd September 2006, 21:56   #10
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Maybe the failure can be attributed to any of the mentioned reasons, However I agree its best to have the ECU Spew the DATA. For best Diagnosis.
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Old 23rd September 2006, 02:59   #11
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Elf, I would like to know how you have narrowed it down to cylinder number 2. Please give me more details if you can buddy. Also like rocam says have the compression checked. Remember while checking compression to disconnect you fuel pump. This is a must. If you do find compression eratic between cylinders I suggest using a very good engine flush. I think Viper represents OWS. They make the best that i have used. There is a procedure to be followed while flushing. PM me if you are interested nd i will let you know how.

After flushing have your compression checked. Most likely compression should be even with 1 to 2 psi here or there. Do this first and then we will go to the next step.

With regards to eratic idling, have your MAP sensor opened and cleaned. It's the sensor which sits on top of Plenum chamber just behind the throttle body. Also suggest that you have the stepper motor opened and cleaned. Very often we miss this one little guy. Sits just below the throttle body. I think checking these 2 things should sort out erratic idle. There is one more thing but i prefer not to touch it unless absolutely necessary. So do this and let me know. Then we will proceed further. Dont worry buddy we'll have your baby flying in no time.

By the way, have I eve told you that you really crack me up. You are just too funny. Would love to meet with all you guys one day
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Old 23rd September 2006, 03:42   #12
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Quote:
Originally Posted by Sideways
Remember while checking compression to disconnect you fuel pump. This is a must.
...to add to what Sideways said, you can do this by pulling the fuel pump fuse.
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Old 23rd September 2006, 19:52   #13
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Smile Thenk Yhoo...

I figured it was cylinder #2 when I had the injectors cleaned at Pai. We swapped injectors to test, & #2 still stayed funny.

Post that, when the MSD plug wires were installed, we kept the engine on & removed plug wires to check the effect it would have on the uneven idle. Removing each wire one after the other, the idle got worse, except upon removing #2, where there wasn't much difference.

Note that the idle ain't really that bad (IMHO), am just aiming for perfection. Also, my gas mileage sucks. I'm not that desperate for fuel savings, but have figured that something must be wrong somewhere for it to be so bad (7 km/l). People post crazy figures of 11 to 14, which is making me go nuts. If you want to know the mods installed, please visit my garage.

@Sideways. Ford_Rocam, Viper:
Shall do as you guys say. Genuinely appreciate your advice & inputs on the whole issue. Am planning a trip to the Dayaram Santdas pump @ Breach Candy shortly.

Last edited by elf : 23rd September 2006 at 20:03.
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Old 23rd September 2006, 19:58   #14
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Quote:
Originally Posted by elf
[left]

[b] Am planning a trip to the Dayaram Santdas pump @ Breach Candy shortly.
Thank god you finally are doing what i told you. Please make sure that you give him ample time to check/clean everything out thoroughly once and for all. No doing things bit by bit.

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Old 23rd September 2006, 20:47   #15
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Quote:
Originally Posted by wolfinstein
Hey guys, another problem has started....!

The RPM goes up and down ( 800- 1000) at Idle speeds, The engine takes more RPM than speed when moving first gear..and on road whenever I speed up..the RPM reves more than the speed ( RPM goes 2000 and then comes down to 1500)..!
This happened a few months back and got resolved on its own...I was suspecting a dirty throttle since the engine is timed and tuned..! The dealer confirms my suspicion..However I wanted to know that...Till date I've never had to clean the Fuel Injectors...! Whenever I myself asked the Showroom Service Tech to do it, I was advised that they are fine and don't need cleaning...So should I take their advise or should I go ahead and do it anyway...!

Does a dirty throttle cause Surges in RPM...!
Impure fuel has been known to malfunction the injectors due to the eventual deposit of dirt. You should, in all probability, get them cleaned. Assuming that clogged injectors are the problem here, the varying RPM you've experienced is answerd. If the ECU detects spontaneous starvation of fuel at any cycle, it signals more fuel to be available during the next combustion cycle. Conversely, if there's more fuel injected via the previous statement, the ECU dictates lesser fuel to be available next.
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