running issue
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
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From: N.C.
running issue
so i have tryed starting my seven over and over again, and its the same thing over and over. its seems i have a case of hot start with a fuel/air issue. the car has 550' prime and 720 secs could this be flooding my car out ? also it will start and when i go to give it gas its a very slow rev in rpm's as if the fuel isint spraying but it could also be from too much fuel going in at one time. the car hasent been tuned for the 720's i just put them in for compensation reasons. i have a set of 550s i can replace them with just haven't done it yet. so really what im asking here is how do you fix hot start and why would the car keep killing its self? i talked to another member on the forum about a problem he had that was along the same lines and he said that due to it being a fresh rebuild i need to prop open the afm and set my idle screw for 1500 to try and keep it alive i wont be able to try any of this till probably sat. but im just looking for options to get this thing going its been sitting far too long. another thing that happen is we worked on it all day yesterday with no start today we showed up charged the batt for a bit and turned the key car fired right then died.
The secondaries have nothing to do with it. They don't fire until 3800+ rpm.
You likely have really dirty primaries, or just a low compression engine. Test it & send the injectors out to be cleaned.
You likely have really dirty primaries, or just a low compression engine. Test it & send the injectors out to be cleaned.
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
Likes: 0
From: N.C.
If this fresh rebuild has abnormally low compression, it's going to be hell to get it started & then keep it running under say 1k rpm. Go ahead and do whatever you can to boost the idle speed, but only a compression test will give you any useful information. Not all rebuilds turn out ok, so it's something you'll want to know.
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Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
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From: N.C.
once the key is relaxed from start to ON, if the engine is running then the fuel switch inside the afm is MADE, and the pump keeps on running. IF the switch in the afm is not MADE, then the pump stops once the key is not HELD to START anymore.
Simply jumpering the yellow, two socket fuel pump check connector overcomes the switch inside the afm and the pumps keeps running anytime the key is to ON or better.
Just jump the fuel pump connector, and see if that helps. I don't know if it'll do anything. If you can put some miles on it, you'll at least get an indication of whether or not it will get better.
I know on a S4 its on the passenger side of the engine, S5....I dunno, Ive had this S5 for a week and still learning about it lol
All im seeing is that idle speed is computer adjusted by the BAC
All im seeing is that idle speed is computer adjusted by the BAC
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
Likes: 0
From: N.C.
what ive been trying it hte method hailers told me hold foot ot floor to use the factory fuel cut and spray starter fluid to try and get it running and then once i have an initail start pat the gas to keep it alive but seems i cant keep it running is it just due to low comp ?
Full Member
Joined: Aug 2005
Posts: 83
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From: Cairns, Australia
30 on a FRESH REBUILD?
WOW! I'd be going to whoever did that rebuild and getting it done again, I'm fairly sure you have no chance of getting a car to start let alone run with numbers that low.
Are you sure you read the numbers right? I'm fairly sure you won't even get it started with numbers lower than about 60, and even at 60 or so it's VERY hard to start then.
WOW! I'd be going to whoever did that rebuild and getting it done again, I'm fairly sure you have no chance of getting a car to start let alone run with numbers that low.
Are you sure you read the numbers right? I'm fairly sure you won't even get it started with numbers lower than about 60, and even at 60 or so it's VERY hard to start then.
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
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From: N.C.
i was looking on rotary ress and he was saying that 30 was usually what was seen on fresh rebuilt engines with old housings and new seals, i knew my numbers were low hince the hard starting but then again i wasn't completely sure on how to use the gauge either.
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
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From: N.C.
Old parts have a certain amount of wear and tear on them. Mazda has specifications which account for this little bit of wear when deciding whether a part is re-useable or not. A used part that is within spec is not perfect, it's just close enough that it considered to be ok to use.
When a part starts to wear, it never wears perfectly evenly. Quality new parts are fabricated to within very tight spec. Usually any imperfection is so small that it is not noticable when you look at the part. However, when trying to compress ari/fuel the mix of wear on the used part and the imperfection on the new part may not make very good compression. This is because both parts will have slightly high and low parts when they press together to make a seal. Natually, the high parts will wear quickest and as they do more of the seal will actually touch what it is sealing to, which will equal better compression.
Exactly how long it takes a rebuild to fully build compression (the apex seals to seat) depends on the condition of the used housings and the kind of apex seal being used. Some will have good compression almost right away and some will take quite a while before they have good compression.
As for the hot start issue, I really don't know an explination as to why a rotary with low compression won't start while hot, but they do. I'm not sure if there is an exact number where someone can say for sure there will be a hot start issue or not, but I know when I got my car it had 90psi front and 60psi rear (thanks to 2 chipped apex seals and 2 cracked corner seals) and it would flood EVERYTIME I tried to start it with the engine hot. I don't have compressions number post rebuild, but I never had a hot start issue after the rebuild so I assume the compression is good.
90psi is a general number too. Exactly what condition an engine compressing to 90psi is in depends on the engine. A S5 N/A (9.7:1) that is compressing to 90psi is showing more wear than a S4 Turbo (8.4:1) (I think thoes compression ratios are right but i'm too lazy to look them up). Either way, compression will be lower than normally desireable. However some engines can last quite a while on 90psi.
When a part starts to wear, it never wears perfectly evenly. Quality new parts are fabricated to within very tight spec. Usually any imperfection is so small that it is not noticable when you look at the part. However, when trying to compress ari/fuel the mix of wear on the used part and the imperfection on the new part may not make very good compression. This is because both parts will have slightly high and low parts when they press together to make a seal. Natually, the high parts will wear quickest and as they do more of the seal will actually touch what it is sealing to, which will equal better compression.
Exactly how long it takes a rebuild to fully build compression (the apex seals to seat) depends on the condition of the used housings and the kind of apex seal being used. Some will have good compression almost right away and some will take quite a while before they have good compression.
As for the hot start issue, I really don't know an explination as to why a rotary with low compression won't start while hot, but they do. I'm not sure if there is an exact number where someone can say for sure there will be a hot start issue or not, but I know when I got my car it had 90psi front and 60psi rear (thanks to 2 chipped apex seals and 2 cracked corner seals) and it would flood EVERYTIME I tried to start it with the engine hot. I don't have compressions number post rebuild, but I never had a hot start issue after the rebuild so I assume the compression is good.
90psi is a general number too. Exactly what condition an engine compressing to 90psi is in depends on the engine. A S5 N/A (9.7:1) that is compressing to 90psi is showing more wear than a S4 Turbo (8.4:1) (I think thoes compression ratios are right but i'm too lazy to look them up). Either way, compression will be lower than normally desireable. However some engines can last quite a while on 90psi.
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
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From: N.C.
also i have sat down and read some thing in the searche's i have been doing
so i always start my car with gas foot floored
spray some starter fluid in the TB
and try cranking car will somtimes kick over, then as soon as it turns i give it some gas and it will run and show RPM's a lil swoosh from the BOV and then it will start to fall and i'll floor the gas to try and keep it alive then dies, and wont start again. somthing point ot injectors others to compression i just dont understand why when i try to give it gas it dies. if i could figure that out the car would run.
so i always start my car with gas foot floored
spray some starter fluid in the TB
and try cranking car will somtimes kick over, then as soon as it turns i give it some gas and it will run and show RPM's a lil swoosh from the BOV and then it will start to fall and i'll floor the gas to try and keep it alive then dies, and wont start again. somthing point ot injectors others to compression i just dont understand why when i try to give it gas it dies. if i could figure that out the car would run.
Hmmm.. my engine with 60 psi front and rear starts up fine. I just have a kill switch to the fuel pump. But this is the first week for the 6 port turbo with 60 psi on front and rear.
Thread Starter
10 pounds sounds so nasty
Joined: Sep 2006
Posts: 399
Likes: 0
From: N.C.
see thats the thing
lol see thats just it, i can get it to start its running part im baffled on she only wants to run a few seconds before it dies and then i have a pain trying to get it fired back up and if i do same thing again. it will start run for a few seconds with me patting the gas then when she starts to go down in RPM's i floor it to try and keep it going then dies.
Joined: Sep 2005
Posts: 25,581
Likes: 136
From: Smiths Falls.(near Ottawa!.Mapquest IT!)
Is your AFM plugged in?..if not,it will start and die,like you are Saying it does when you try to start it.
I am thinking you disconnected the AFM to get at the intake with quickstart fluid(Ether).
I am thinking you disconnected the AFM to get at the intake with quickstart fluid(Ether).