So my friend just bought an S5 NA with full rebuild streetport, 110 compression, open exhaust, aftermarket intake, and no aux ports.




1: He brought the car by my house so I could look over a few things(being the owner of an FC that has had many many problems has given me a small bit of experience) So the first thing I told him when he brought the car by my house was "your going to need a tune for this thing to run at it's full potential". Although everything seemed to be running/working great, the only problem I noticed was that the car took about 5-6 seconds to start up, although not a big problem, it did catch my attention.



2: So here we are 2 weeks later, and his car will NOT start under it's own power. We have to push the living **** out of it to get it to bump start, and even that only works 1/10 times. First thing I suggested was to "check, and replace the plugs if needed" and INDEED they were mildly fouled, and replaced.


3: So with the new plugs, the car FIRES right up first try. I tell him "see? sometimes it's as easy as that"....... Well, we turn it off, and try again and... NOTHING. Same thing as before. Just keeps spinning and spinning and spinning. At which point I came to the conclusion that the car is flooding. So I try the S5 full throttle flood clear start, and nothing.

4: By now we're getting very irritated, and we use the frustration to push the **** out of the car for one last try and a bump start... IT WORKS, so we get the car running, it does the usual warm up deal 1500-2000 idle, and slowly dropping to ~900. We let the car start to warm up, at which point the idle starts dropping to around 600-700, and is a little erratic. Totally normal for a streetported motor I suppose??

5: Here's the confusing part. I know the car is most likely flooding, which explains most of the problems. Except for this last issue.

When I noticed the idle drop a little low, I got in the car and attempted to try and keep the RPM's high, just to make sure that the car didn't shut off. But when I did this, the car started bucking, and bogging, and then the motor just fell flat on it's face, and shut off indefinitely.

Can someone please shoot me a few things to try tonight??? I really wanna help this guy get back on the road. Any input is appreciated.

I do have a few suspects though, mainly the AFM

 

i believe you are looking in the opposite direction, check fuel pressure and voltage to the pump and it may be too low.

flooding and lack of fuel both give the same result with rotaries, except flooding will usually give you a random pop/hiccup here and there. lean conditions usually result in stalling, not so much if the engine is running rich so my assumption is the pump is dying or the pump wiring is going out.

 

Cool thanks man. I was talking with RadioX7's dad last night, and we both brought this issue up. The car did after-fire one time while bump starting, which is what led me in the other direction.

 

well i very rarely see engines with flooding issues if the compression is in fact 110+. i've run turbo cars with 750 primaries and non turbo cars with 550 primaries on bone stock ECUs and if the engine is healthy it will have no starting problems. unless someone put in some rediculously large primaries i wouldn't suspect it to be dumping too much fuel.

cranking fuel amount is static, so either one injector isn't firing properly or it's dumping way too much fuel somehow. checking fuel pressure would still be my starting point.

timing may also be a problem, if it is way out the engine may still start and run somewhat normally but it will be a bear to start. timing can be 180 out and still run, since the leading ignition will still fire properly but the trailing will be firing early on the intake stroke.

 

Check the connectors to the injectors? However if one injector wasn't firing at all (i.e. not connected properly or a faulty connector) than it would run like absolute crap.

 

I will try and check fuel pressure later. I just don't see why it would run fine for a minute or two, and then fall on it's face.

Could it be a faulty sensor, combined with not going into open loop? or something like that?



Thing is, when it runs, it runs fine(until random shut off). It's just damn near impossible to get going.

 

Probably not a faulty connector then, unless it's really loose or something? Id do what Karack says, usually always a good route...

 

i never take anyone's idea of running properly at face value. i have had numerous cars come in with idle screws cranked in, running on one rotor with a simple explanation of "the car hesitates when accelerating".

these were people with rotaries and with friends who owned rotaries. not everyone knows exactly what a single rotor sounds like when firing. won't even go into how many were blown and driven in with the same explanation.

i also never take anyone's word on previous compression tests, but here we have no choice.

 

its been my experience that when you open the aux ports, it can take a few more revolutions for the engine to start than normal.

however, they will start, and after you look at fuel pressure, the engine coolant temp sensor plays a huge role in fuel at start (when the ECU sees start its rpm + coolant temp only).

vacuum leaks matter as well, timing should be checked, and you should check compression if you didn't do it...

 

Most people base their comp. numbers off of hopes and dreams, but we actually have a print out from Lucky-7 Racing




I will definitely look into that!


. I have a question though, since there'd really be no way for me to check fuel pressure tonight. Can I **temporarily** swap in a T2 fuel pump? SOLELY for testing, this will NOT be used permanently. I don't have any spare NA fuel pumps, only a T2

 

have you checked voltage on everything?

how fast is the starter even spinning, a weak battery will make the car hard to start.

Rotary > Pistons

 

yep.

 

this is a long shot, but if you have an extra leading coil, swap it and see if it makes a difference. i had a coil pack that once worked erratically.

 

Thanks man. Will do, I've been out of contact with the car for a few days. So I have quite a few things to try when i see it