4500rpm rev limit and malfunction light flashes on.

Anonymous · September 17, 2009, 02:14

Was wondering if anyone could offer advice or any ideas. My engine revs up to 4500rpm when im driving then it hits what feels like the rev limiter and the malfunction indicator light flashes but it does not stay on. from idle to 4500rpm the engine sounds and feels fine.

I've searched the forum but most results bring up people who have had a faulty o2 sensor but my symptoms seem different as their malfunction light stayed on.
Done ecu reset and cleaned maf, problem still there.
Im hoping its not pre cat failure? going to get a sensor socket so i can look in the manifold and OBD reader tomorrow hopefully, just wondered if anyone had a similar experience or ideas as to what the problem might be in the meantime.

Anonymous · September 17, 2009, 07:17

Flashing CEL is a very bad misfire (as opposed to just a slight misfire) and the car should not be driven until the problem can be diagnosed. The lack of revs would normally suggest pre-cat failure, but not usually with a flashing CEL. Check the precats to rule them in/out and read the code and then we'll have to go from there.

uktotty · September 17, 2009, 10:50

Take the 02 out and check the state of the precats or find a local member in Surrey. Nige??

muffdan · September 17, 2009, 11:47

pre-cats are probably fine or at least not the cause of the rev limit symptom. The inability to rev past 4500 is simply because it's seriously mis-firing. When I've had this issue, its felt and sounded like the ECU has momentarily shut off the coil packs as it flashes the CEL. This pretty much makes it impossible to rev through the misfiring.

Anonymous · September 17, 2009, 22:37

Is this the ECU going to limp mode to avoid damage to engine?

Anonymous · September 18, 2009, 20:53

I was going to ask this question too about limp mode. I only got round to ordering the code reader and sensor socket today so i will have to wait and see what code comes up.
Thanks for the replies by the way guys, do you think its ok to drive it to my friend's garage staying under 4500rpm so he can check it out? He's also got a code reader so could get the code read sooner. He suggested looking at the coil packs and i've read quite a few posts about them so this seems a strong possibility as the car was unused for about a month, assuming that the code shows up a misfire that is.

enid_b · September 18, 2009, 23:34

no. i would not recommend driving it at all. limp mode is designed to get you home when you are mid journey. even staying below 4500 you are taking what i would consider to be an unecessary risk.

muffdan · September 20, 2009, 14:18

I don't think its limp mode, surely the CEL would be on permanently if it was in limp mode?

Anonymous · September 20, 2009, 15:38

Quote from: "muffdan"I don't think its limp mode, surely the CEL would be on permanently if it was in limp mode?

I dont think so,I believe the flashing CEL is the really serious one.

muffdan · September 20, 2009, 15:45

yes, the flashing cel means serious misfire but if the ECU was running in emergency-take-me-to-the-garage-quickly mode, don't you think it would have the cel on all the time?

I can't see it being in limp mode without having some sort of visual indication to the driver that it is.

Anonymous · September 22, 2009, 16:46

Right, i got the code reader today. Its says no DTC codes. But the I/M readiness reads 'no'. In the I/M menu everything reads either 'ready' or 'N/A' except for CAT which reads 'not ready'.

also forgot to mention that the engine wont rev past around 5000 in neutral with no engine light coming on. Havent got the o2 socket yet hopefully come tomorrow so i can check precats. Oil level is still full. Is this indicating more towards precat failure? This is what im thinking.

Anonymous · September 22, 2009, 17:45

Quote from: "xlzroc"Right, i got the code reader today. Its says no DTC codes. But the I/M readiness reads 'no'. In the I/M menu everything reads either 'ready' or 'N/A' except for CAT which reads 'not ready'.

also forgot to mention that the engine wont rev past around 5000 in neutral with no engine light coming on. Havent got the o2 socket yet hopefully come tomorrow so i can check precats. Oil level is still full. Is this indicating more towards precat failure? This is what Im thinking.

With precat/oval bore syndrome you usually find you have no oil in the engine or that its burning it pretty quick.

muffdan · September 23, 2009, 09:37

I wouldn't drive the car until you've checked, just in case.

Anonymous · September 23, 2009, 10:19

Quote from: "xlzroc"also forgot to mention that the engine wont rev past around 5000 in neutral with no engine light coming on. .

I may be from the "old school of motoring" - given that I've got grey hair - but I don't think ANYONE should be trying to rev their engine over 5000 RPMs in neutral!.

As you know there are a myriad of reasons why your CEL light could be illuminated. But don't avoid checking the obvious. If the *MAIN CAT has started to break up and block the exhaust it could create a great deal of back-pressure in the pipe...making the engine labour under increasing revs...

(*I'm no expert but I had a CAT go on another vehicle. Like many modern cars SOME of the exhaust gases from the engine were recycled - for a second burn - to improve emissions. I believe the build up of pressure - after my CAT broke up forced excessive volumes of burnt gases back through the system - as well as (I ASSUME) via the exhaust valves...which had the effect of smoothering the engine as I put my foot down! PLUS the car would loose power as soon as I tried to go up hill!!).

just a thought...fingers crossed it's something straightforward!

Good luck

Dave

Thudd · September 23, 2009, 12:10

Is it the vvt-i failing? Should change around 4500.

Anonymous · September 23, 2009, 12:19

Quote from: "Thudd"Is it the vvt-i failing? Should change around 4500.

i think there is a control box for VVT-i

Anonymous · September 23, 2009, 12:49

Quote from: "Thudd"Is it the vvt-i failing? Should change around 4500.

The VVTi works across the whole rev range, that's why it's called variable s;)

s;) There is no kicking in point like a V-TEC or VVTL-engine.

Anonymous · September 23, 2009, 13:04

Quote from: "Dan M"
Quote from: "Thudd"Is it the vvt-i failing? Should change around 4500.
The VVTi works across the whole rev range, that's why it's called variable s;) s;) There is no kicking in point like a V-TEC or VVTL-engine.

i stand corrected i thought it moved the timing around that RPM to improve power s:bowdown: :bowdown: s:bowdown:

kanujunkie · September 23, 2009, 13:06

Quote from: "rbuckingham"
Quote from: "Thudd"Is it the vvt-i failing? Should change around 4500.

i think there is a control box for VVT-i

no there isn't, its oil controlled

Wabbitkilla · September 23, 2009, 13:24

I'm sat here wondering if there's something wrong with the knock sensor, or crank position sensor - or even their wiring?

Not enough to give an outright code, but enough to affect the running of the engine.
Even a lose earth strap as it moves under acceleration?

markiii · September 23, 2009, 13:41

do you have good oil pressure? do you have oil?

have you checked teh compression?

Anonymous · September 24, 2009, 11:54

Hmm. this is a real chin scratcher. I think L.O.B. and others are right about your car running in 'limp mode'. In which casethe rev limit issue IS NOT necessarily related to the problem area - it's just the ECM doing its best to protect your engine!

Is your car an import? If so, have you bought the right code reader? I ask because I simply can't believe there are no codes registered/pending - given the scenario.

I think you might have more success finding the cause of the problem with a PC based software package like OBDPRO using a ELM327 (or clone) link via your diagnostic socket.

Do hope you manage to get it sorted without too much expense...

4500rpm rev limit and malfunction light flashes on.

uktotty