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i bought a new motor from chrismotorsports. dropped it in with new plugs, coils, wires, MAF, ess, Throttle body, cleaned o2 sensors since they were practically new, new fuel pump, starter (series 2 13 tooth), and new 1100cca gel battery. I get good consistant spark through a timing light on each wire. i get it started cold with minimal hesitation. it runs great no power loss, but my idle will occasionally drop to 500 or just straight stall. when this happens and in general i cannot hot start the car so i need to wait 30min to get her going or bump start her. Ive been gaurenteed its no low compression and it disn seem like it when i checked it (but ive been diagnosing this problem for 3 weeks now and its been hell) any help would be great. i do have access to an series 2 rx8 to try swapping parts from there in order to make sure my new parts arent duds from the factory and so far its just proven that everything is working... i also have a cobb and a live monitoring obd2 scanner to use to map any systems if needed. so yeah any idea would be great since ive read all these threads 10 times now and im still at a loss
Drive it for a few hundred miles and it should be better. It takes a bit for everything to bed in after a rebuild. If you still are having problems then check the compression
Are you sure you have the Secondary injectors hooked up properly? It is really common for them to be installed wrong and the car will idle and run like crap
So I'm at 387 miles on it, and I'll gladly keep going but I thought that'd be enough to break in. AS for injectors being hooked up poperly, you may have something there. When I read installed the harness there was really only one way for the wires to connect to the injectors and actually have all of them connected so I think I got it right but who knows. Do you know where a diagram would be for which wire matches which injector? I'm not pulling anything up at the moment.
Also thanks for the quick response. This forum is always fantastic
Basically you are injecting fuel into the wrong place....and the injector sizes are different.....so could cause both. It also causes problems higher up the rev band as well....but you likely haven't been there yet
Basically you are injecting fuel into the wrong place....and the injector sizes are different.....so could cause both. It also causes problems higher up the rev band as well....but you likely haven't been there yet
so i followed this diagram and everything was plugged in properly. still no hot start and now idle slowly just gets worse and worse with heat until it drops to 500 and stalls. before i could get it to idle in one place for over an hour which is what chip (the engine builder) reccomended i do in order to fix this. as for the higher rev band i drove it up to 9000prm a couple of times and it definitely felt like it had plenty of power, whether or not it was all 220hp i cant tell but it felt quick like it used to. so now im at a loss again haha
This is my second throttle body and I know it's a good one but my mad is reading about 6.7 g/s near idle and 12.5 at 2500rpm.
My short term is either -5 or +5 it's jumpin around like crazy and long term is chilling at 0
Sounds like compression then...drive the car and see if it gets better. It should over about 1000 miles. If it doesn't someone screwed up something in the rebuild. There really shouldn't be compression issues like that with a proper rebuild though...usually they don't require that much run-in
Okay I'll do a 500 mile trip this weekend to visit my brother to see if that does it. AND yeah chip is a bro and from the pictures I saw of the build there should be no issues so I trust him and his skills.
So update: was driving and it was idling pretty well for about 30miles then I tried to push the envelope and drive it higher rpm for an extended period of time and it was going great driving with all the power in the world then it began to surge blew a pending p0300 and at higher rpm the whole car would shake back and forth lost almost all power and wouldn't idle. I nursed it to a hill parked it checked all my connections and they were good (then bump started it since ya know, no hot starts still). When I started back up it didn't surge when I was going over 4000rpm like it was. I'm thinking maybe I bought faulty coils? (I had my timing light on the wires before and they seemed fine with steady spark but maybe they can't function in the heat which kinda makes sense for the hot starts)Since it seems like maybe it was heat related. OR maybe it was fuel related but I doubt it since it's a brand new dw200. I have 3 used coils I know work so I'm gonna swap those on and see what happens tomorrow.
UPDATE: so im going to mazda this week to get an official compression test for 150bucks and then most likely returning the motor. i cant fathom how its got low compression but using a standard compression tester it keeps running low compression and im now over 1000 miles on the block and it still refuses to hot start and it will stall at some stop lights but not all which means whenever i drive it i need to push start it if i want to get it going after i turn it off. if it is compressoin as i think i guess ill be parting out my rx8 and selling my custom turbo build since 3 engines in 6 months is making me miss my v8 heritage
I have almost a similar problem, rx8 2004 model wont stay idling. When i release my foot off the gas paddle or when i try to engage into drive/reverse it runs off, what could be causing this? Kindly help..
I have almost a similar problem, rx8 2004 model wont stay idling. When i release my foot off the gas paddle or when i try to engage into drive/reverse it runs off, what could be causing this? Kindly help..
Depending on the miles and last maintenance it could be a myriad of issues. If you haven't done any if these items in 10000-30000 miles I would:
- check engine light on - if so take it to auto parts store to read codes
- get the air/fuel ratio correct by:
changing the air filter
cleaning the MAF sensor with MAF sensor cleaner
- get the ignition healthy
replace coils, plugs and wires
- run Techron fuel system cleaner
- check for loose vacuum lines
Find out how to do all these by running a Google search for this site by:
Depending on the miles and last maintenance it could be a myriad of issues. If you haven't done any if these items in 10000-30000 miles I would:
- check engine light on - if so take it to auto parts store to read codes
- get the air/fuel ratio correct by:
changing the air filter
cleaning the MAF sensor with MAF sensor cleaner
- get the ignition healthy
replace coils, plugs and wires
- run Techron fuel system cleaner
- check for loose vacuum lines
Find out how to do all these by running a Google search for this site by:
Thank you very much. My mileage is at 101444 KM so I'm suspecting i have leakage in vacuums and i need to change the air filter and get the MAF Sensor cleaned
well Im new to the RX8 world. I just bought an '04 and when it warms us it stalls when I press in the clutch but only periodically. sometimes it is fine. I have cleaned the maf and tb. no check engine light the coolant light is on but thats it. Anything else I should check before having mazda have a look at it? Starts right back up no problem.
ok guys look im thinking about buying an 05 Mazda RX8 but the guy selling it says that it has trouble starting when its hot or cold so im taking that as when ever really but also when it does start it has a rough idle im just trying to see if its an easy fix or whatever or if its even worth my time and money
The S1 starters are known to be weak, rough idle could be multiple things as simple as MAF and ESS need to be cleaned or could be something more expensive such as ignition system failing or a vacuum leak.
With basically no information about the car and no data that's about as much as anyone can tell you.
Hello, hopefully this doesn't just turn into a massive wall of text but I have a problem that doesn't seem to be covered by the threads I've been able to find, or at least my problem seems different enough that I don't think those threads are totally relavant. I'm going to try to give every piece of information i think could be of use, and what ive done already. I hope there's someone here that could give some insight on this.
last year I blew my engine. Me and my dad (a licenced mechanic for many years) recently finished installing a used motor I bought off kijiji but it seems all signs are pointing toward this having low compression as well. The engine I bought was rebuilt 30000 kilometers ago and looking through the plug holes I can see the nice shiny apex seals and I didn't see any scoring through the intake ports which lead me to believe that it'd probably a better bet than what I could get from one of those sketchy "official jdm imports" dudes. I know it was carbon locked since I've had it in the garage for months before we even got it on the stand, so I did that atf/mmo trick im sure we've all heard about and It definitely made a difference.
Once we got the engine in, it was very difficult to start which I assumed was because of the atf (and I'm probably at least partly right), but after I got it going it warmed up and idled fine. Then we put the airbox and ducting and wheels back on and went to take it for a test drive. It started, warmed up, and idled normally like before, but once I got to the end of the street the car stalled. This is exactly what i/the car did:
I accelerated gingerly most of the way, toward the end I gave it like 3/4 throttle up to 7000rpm, it maybe seemed like it was somewhat down on power at one point but then again I haven't driven it in a while so I can't remember what the power band is like. Then i started slowing and downshifting carefully, then I engaged the clutch and shifted into first from second while coasting off to where I was going to turn around. The car at some point during that just turned off without any sort of lugging or misfire. I turned it back on and it took probably 5 seconds or more to start up, again without any misfiring. I drove it back to the garage and again it died just like before as I was pulling up to where my dad was. I started it up again with a little difficulty after maybe a minuit and it held it's idle fine. My current theory was that this was some how related to the very low fuel level and the old gas so I decided to take it to the gas station and fill it up with 91. About half way there it stalled at a stop sign and it was putting up much more of a fight when I restarted it this time and was misfiring. I chalked the misfires up to the gas again. Right in front of the gas station somebody slowed right down to turn in so i, knowing what would probably happen, quickly pulled off to the side where I stalled out. This time I couldn't get it going at all. I called CAA and their driver was going to be a while so I had lots of time to play around with it. I went through the forums trying out every technique I could find for starting a floded engine and nothing. A few times I waited 10 or 15 mins between attempts. Finally I got fed up and just started cranking and playing with the throttle a little whenever my gut told me it needed "help" and after not too long I got it going. It was misfiring again and I would need to do this to start it every time from now on. In addition to the ridiculously difficult start, it now will not hold idle no matter what where as before It would only stall at idle after a bit of driving. I need to keep the revs up manually or It just dies. Anyway it ran like crap all the way back from the pumps, but every time I've started it since there haven't been misfires.
So here's why I'm feeling confused about wether or not it's a compression issue:
I havent been able to find any posts about idle issues like mine. There are lots of people who stall at idle, but apparently their cars get all bottom endy and lugg themselves to deth whereas the revs in my car fall smoothly from however many rmp to zero. It's like it doesn't even try to catch it. This kind of plays into the weird way I have to start it. If I can crank it up the point where the car would usually "take over" and fire, I need to push it that last little bit before it starts really running if that makes sense. I haven't been able to find anybody who had to use the throttle to help get their car started, but maybe I just don't know the search terms to use since I obviously can't describe it very well as it is.
Plus when most people talk about their low compression, they usually seem get it running with just longer cranking and then don't start having any problems until it gets hot. If I'm experiencing really poor compression I'd assume there would be pleanty of people out there describing the same thing That s happening to my car.
Here is what we have done so far:
We checked for vacuume leaks and there are none. We checked the maf and the sensor itself is fine but there is a slightly cracked o ring (I don't thiink this is a problem, but I'll replace it if nothing else works). We hooked the car up to this snap on scantool thing and it didnt give much useful information, but there is a code stored for o2 sensor 1 but that could maybe have been there since it ran last year I don't know. We also used this to measure the intake pressure while cranking with fuel cut off and my dad said it seemed low (this is one of the things leading me to believe its compression related, but we don't have any normal numbers to compare to and my dad only has an idea about what's normal for piston engines so again, I don't know). Before I started the car the first time I did that 20x break petal stomp thing and I did it again after it stalled the first time. When we take the spark plugs out they are dry so no flooding. My dad borrowed a Mazda rotary compression tester but it was giving nonsense numbers (dealer confirmed it's not working) so he did it the ghetto way with a normal compression tester gauge and apparantly it gave poor numbers but since it's not the right tool for the job who knows how accurate that is. I have brand new oem coils and wires, no cat, and my spark plugs are fouled but they aren't so bad that they'd be the problem. The CEL hasn't come on once since it's been started.
On Friday I am going to pull out the spark plugs and squirt some atf fluid a couple of times (bumping the starter in between) and leave it until Monday to see of this will fix anything. If compression is the only problem here it might be because I never fully cleared out all the carbon and gunk from before and all the seals became stuck again since I've been driving it. That would be a nice solution. Can carbon lock decrease compression like that? The engine was sitting since early November (climate controlled with ports covered though) and who knows how long it was out of the car before I bought it.
Are these symptoms of low compression or other problems or possibly both? If you've made it this far thanks for your time, hopefully you might he able to help
What you really need to do is get a decent OBDII reader and give us information like Mass air flow, fuel trims (LTFT & STFT), AFR, MAF voltage, coolant temps, etc etc all at idle.
Have you cleaned the ESS at all? Its prone to getting metal gunk stuck to it as it is magnetic (Essentric shaft sensor located below crank pulley)?
It doesn't sound like a compression issue but that doesn't mean much. Rule number 1 when buying an rx8 or an engine for it, get compression test results before purchase!
10-27-2016, 12:39 PM
