grisdale

Figure out what’s causing my rough idle and I will Bank Deposit/PayPal you $100 NZD!!

I purchased a 2003 RX8 Type S (6 Speed Manual) about 8 months ago (75,000KM’s), I’ve had 5 mechanics look at it and $7000 later it’s still idling rough.

When it idles it sits between 800-830 with the electronics/aircon off. With lights and rear window defogger on it sits around 820-840 and the vibrations are a lot worse. The vibrations can be felt all over the car, I notice it in both seats and steering wheel but that’s the only part I’m touching.

If I have the car running and open the hood I can see the engine slightly shaking as well as the air intake and airbox. These are constant vibrations but as the idle adjusts you can also feel strong pulses. If I push the RPM to 1000 the vibrations are completely gone and it will be smooth until I let off the gas. If I let the idle drop back to 800 there will be very strong vibrations as the RMP hits 800 then the vibrations will soften and come at a constant rate with intermittent strong pulses.

I have had the following parts replaced in this order:

Full Service and Inspection by Mazda
New Battery
New Spark Plugs
New Air Filter
Full Engine Rebuild
New Starter Motor
New Oil Filter
New Air Filter
New Spark Plugs
Throttle Body Cleaned
New Fan Belts
New Engine Mounts
Post Rebuild Service
New Coils
New Ignition Wires
PCM Flashed to latest JDM version

I have also tried doing the following procedures:

Cleaned the MAF
Cleaned the Eccentric Shaft Sensor
Cleaned Air Intake
Tried Removing Air Intake shields and side buffers
Reset the ECU via brake stomp and odometer button
Disconnected the battery for 30 mins

I run 95/98 fuel, the car runs awesome while driving, dont notice any flat spots and it has lots of power. I don't know much about cars so if you could include instructions with your ideas that would be much appreciated.

I’ve tried to give as much information as I can but if you want to know any info please ask. I also have a cheap ODB2 reader so am able to get readings from the ECU if required.

Easy_E1

iTrader: (2)

How long ago was it rebuilt? Do a compression test and a vacuum test and let us know the results.

grisdale

It was rebuilt about 2 months ago, it had the issue before and after the rebuild. I got it rebuilt because of the rough idle, but it was also running bad and wouldn't start when hot. Ill see if I can find somewhere to get those test done.

Brettus

iTrader: (2)

where do you live ? - if near Hamilton I could take a look at it for you .

grisdale

I live in Auckland so am happy to drive down if you think you could help. So far I've had the following places look at it:

Fast4s - The place I purchased the car

North Harbor Mazda - First Service and Inspection

Street Systems - The place who rebuilt the engine

Endeavour Motors - Place I took it to after the rebuild to get repaired as alot of stuff was put back together wrong

Hyde Automotive - This guy is a friend who compared my car vs my friends working 2003 RX8 Type S to confirm mine definitely wasn't running normal (post rebuild).

A couple of friends who work on their own cars have also had a look.

pottsy

Tried Tony at rx7 heaven in East Tamaki? Nice guy to talk to and recently did some work on my 8.

Brettus

iTrader: (2)

hmmm - well i can't promise i could do any better than those guys ......
But i do have a self tuned 320whp turbo 8 and know these engines inside out . If nothing else you might like to see what power does for an 8

grisdale

Awesome thanks for this, ill flick him an email.

grisdale

Damn that's awesome, thanks for the offer ill keep this in mind

Arca_ex

iTrader: (10)

Well I had a problem similar to this. Actually it just came back, I'm getting my car ready to go to the dealership for its final compression test before the warranty is up, and I got the same sort of vibration that you're having when I took my grounding kit off the car. Is there somewhere that you could have the alternator bench tested? I know here in America you can go to O'Reilly's and they can either test it while it's in the car or bench test it on their diagnostic booth. Reason being is that when you have more draw on the car with lights etc. it gets worse. Maybe the alternator is struggling, the grounds aren't ideal or the alternator could be on it's way out since I assume that you swapped the old one over to the new motor.

First thing that's cheap to try out is unbolting all the stock ground locations and taking a dremel with a wire brush attachment and take the paint off and clean up the ground wire contact surface, I found out that the contact area isn't actually bare metal, it's all painted and paint makes for a shitty ground. Not to mention that all the ground wires are of pretty wimpy gauge wire as well. Next suggesting is maybe try out a grounding kit? But I'd hate for you to throw even more money at it and it turns out not to be the problem...

This is the one I have btw, I'm sure it's a ton cheaper for you to make something on your own for testing purposes though.
http://www.maxground.com/mazda.htm

grisdale

Good ideas, ill see if I can get the alternator tested.

Do you happen to know all the earth mount locations? I tried to find these a while ago with no luck. I could just get some wire and test this myself if you do.

04Green

iTrader: (1)

AAHh

Someone beat me to grounds... Click on the $100 in my sig and go to step 9. It has a good link to a grounding kit install that I believe points out the locations. I remember each fender, under the air box, both sides of engine and alternator.

At this time I think the kit is less important than the good connections. You can be the test case for that. If it works for you I may just pull my kit off. Just get some star washers and grease and tighten everything up good. The one under the throttle body is the hardest one to get to. I think the one on the other side is the hardest one to see.

Just get some good conductive grease when you pick up the washers. If something is horribly corroded, wire brush it. Otherwise the start washer should do the trick.

You might want to check out the rest of the steps as well with an 8 of that vintage.

Good luck.

grisdale

I replaced the coils again with the new model: N3H1-18-100C and it seems to lessen the idle shake, the shakes are more of a constant vibration now rather than coming on in strong pulses so its not as noticeable as you can get use to something that's constant.

I got a friend to check the alternator with a multimeter and he said it seems fine. We also tried clamping jumper cables to the chassis and various parts of the engine while checking them with a multimeter and it didn't make a difference to the vibrations or the voltage of the parts so doesn’t seem to be an earthing issue or problem with the alternator

My friends think I'm maybe just being a bit too fussy about the vibrations but when you rev the engine to 900-1000RPM its so damn smooth it makes me want it to be like that all the time. I was going to buy an access port to increase the idle rev's but i've read on here that you can and cant change the idle with the accessport so I'm not sure which is true.

dannobre

iTrader: (3)

You can change the idle...mine idles at a nice 900-920rpm

rickeo

iTrader: (1)

I had MM raise mine slightly as well as its just a little too unstable for my liking. 50RPM and its smooth as butter.

zoom44

grisdale have a look at your PPF. with the work you have had done its likely to have become misaligned or not been reinstalled properly.

pdf attached

nycgps

iTrader: (1)

sounds like something is out of balance in the rotating assembly.

u got the car used right? do u know if the engine is original or someone rebuild it before you got the car?

reason I ask is if it was rebuild before you did, chances are one of the rotors were bad, the rebuilder didn't have much experience and just randomly got some rotor without checking the weight stamp, rebuild it, send it off. or used the wrong balance weight, even a wrong spacer can give u weird results.

did your rebuilder check the weight stamp and all parts before the rebuild? this is often overlooked and will create funny results.

or it could be as simple as PPF alignment like zoom said

grisdale

Hello,

Hmm that PPF thing looks difficult to check, I have no skills at working on cars

I got the car imported from Japan and had the problem since day one, the guy who rebuild the engine for me (Street Systems in New Zealand) had my car for 3 months and managed to make the following mistakes so I don't have much faith in his work:

Forgot to reconnect earthing wires

Bent the pulleys causing the fan belts to snap and shred into pieces

Broke several clips on plastic parts

Cross threaded one of the engine mount bolts

Cross threaded the Coil assembly mount

Didnt properly attach a radiator hose causing all the engine coolant to drain out

Re-installed faulty coils

My clutch is also now making a squealing noise that only goes away when the clutch pedal is pressed in since getting it back, a friend said it could be the push/pull bearing on the clutch and said he possibly got it wet or didn't reassemble it correctly

He replaced one of the engine mounts but the other one was faulty or not sitting correctly so that had to be redone also

Maybe ill call the warranty place back and ask them to send it to a real Rotary specialist since I want them to at least fix the clutch squealing issue as its embarrassing when sitting at the traffic lights.

MariesRX8

My 2004 has been like that for years, both before and after an engine replacement, engine mounts, coils/plugs/wires, etc. It's not a terrible vibration, but there's a very noticable difference from the buttery smooth warm idle falling down from 1000, 900 rpm... to the vibrations that only start once it settles at it's lowest point around 850.

I don' t know if it's "normal," but it sure is common. And like you said, maybe we're being fussy, but it's just sooooo nice when just 100 rpms higher.

Sad thing is I don't think I've read a thread where someone said they had this problem, then did [insert magical procedure], and it then idled perfectly smooth.

grisdale

Damn that's not good news

I've read a tone of threads about people having our exact symptoms then replacing the engine mounts and it resolving the issue but it wasn't the issue in my case.

grisdale

I took my car to Tony and showed him the rough idle issue as well as this squealing problem I have with my car that only goes away when the clutch is pressed. He said he could install some wedges on top of the engine mounts to fix the idle shake and he could replace the thrust bearing to stop the squealing noise. I got him to do the work and asked if I should replace anything else and he recommended doing the clutch at the same time so I went with that.

$800 all up, picked up my car 3 hours after dropping it off. Got home and it still shakes and the squealing noise is still there too. Emailed Tony telling him about the squealing noise and he told me to take it to a gearbox shop as it could be the gearbox bearings.

Got a few people to look at my car and they said its definitely the thrust bearing making the sound. They said the probably a worn pressure plate that could be causing the thrust bearing to make the noise. They have no idea about the idle shake though.

I've send Tony 2 emails over the last 2 weeks asking if he will have another look at my car but hes just ignoring me now.

I wouldn't recommend anyone goes to RX7HEAVEN, what a waste of time and money.

Brettus

iTrader: (2)

So does it squeal when driving or only at idle when stationary with clutch out ?

TOMCATS8

iTrader: (1)

Sound like the throw out bearing for the clutch noise.... I'm subscribing to this to see if you get the vibrations resolved

grisdale

Both moving in gear, moving in neutral or stationary in neutral. The sound goes away as soon as the clutch pedal is pushed down past the freeplay amount (2mm) both when moving or still. My friend also squeezed the slave or master cylinder (not sure what one) with his hand to move the release fork off the pressure plate and the squealing noise completely went away so he said it's definitely the thrust bearing squealing but possibly the pressure plate causing it.

Slidin8

I'm subbing to this as your a kiwi,

just a thought but have u checked you have the latest ecu flash?