christopherdeanerogers

Hi All,

Haven't posted for a while, I have a 2001 Type RS with a large single + PFC + supporting mods, including larger injectors and fuel pump. Standard electrical and spark system.

In short, the car will not start.
It cranks well, but just won't fire. Dont think it is a fuel issue as I can smell fuel while running the starer motor. Not a battery issue as I bought a new one and hooked it up.

It clutch starts fine and runs well. Seems like it still has full power, etc. Will rev out to redline and smoke any V8, as per normal, expected operation.

Only notable running isses are that when you are at cruising rpm and put the clutch to stop the car or coast (i.e. the revs are allowed to drop back to idle), if the revs get too low, the engine cuts out. If the PFC catches the revs before they get too low, there isn't a problem, its only if revs get well below 1K rpm.

Since I did the single turbo upgrades, it seems that this issue has slowly been raising its head. It started when I would find it would cut out when comming to a stop. This became more and more frequent, then it started becomming hard to start, until it got to the stage it is at now.

Keeping an eye on the voltage on the PFC during start up, it will crank with volts siting at around 11.2-11.3V. It will sound like it wil want to start when he volts get to about 11.4. It the volts get to 11.5-11.6, it will fire and start. I can acheive this if the batery is very freshly charged or if a jump start from another car is hooked up.

Does anyone have any ideas on what this might be?
If it is just a tuning issue, that's fine, but I would hate to take it all the way down to the shop only to have them charge me for a new alternator, regulator or something else that I could install myself for half the price.

What voltage does your PFC show while cranking before the 13b will fire?

Much appreciated.

misterstyx69

iTrader: (142)

I'd start with checking voltage at the battery when off.
then check the voltage at the battery when on.

To me it sounds like your alternator regulator is starting to crap out and it won't keep the constant voltage needed to keep the car going...(I've been known to be wrong,but this advice certainly wouldn't hurt to check).

christopherdeanerogers

Whe the car is running, it produces a steady 13.8v, even when I change the RPM. When off, the battery is between 12.5v and 12.7v.

Seems normal to me.

But I did notice that when the car stall due to the revs getting too low, the alternator voltage gets low also, it goes below 12v at 500-600rpm.

Sgtblue

iTrader: (16)

Get a copy of the FSM for trouble shooting hints. Never had these issues, but maybe check coils or low compression for starting issues. Dash-pot or idle air control valve for off-throttle stalling behavior.

christopherdeanerogers

Im sure it is not a compression issue, still have full power when the engine is running, will do a test this afternoon to make sure.

Coils have been tested and are fine.

Will check the dash pot tonight.

Have removed the idle air control valve and blocked the port off with a plate, as part of the single turbo install.

Im sure the issue is related to voltage somehow since it will only fire when it has the right voltage.

89fc3sgtu

iTrader: (3)

Does it crank slow when it wont start is so have battary load tested starting is all about amps not so much voltage and have the started checked of cranking slow started could be drawng to many amps but only it is cranking slow or slower than normal

misterstyx69

iTrader: (142)

This may not be relevant though 89fc..as I think the OP is stating that the car goes below the regular idle and then it starts to act up.
It's like a Idle air control thing I would say..
Thought: that if the car could stay above the "idle" then it may not happen.
Check the throttle stop,throttle plate movement and any device associated with keeping the car at constant idle.
But I can't really say as I am not an FD guy and plus I don't even have that part on my Engine any more.I stripped every bit of crap of it.

christopherdeanerogers

Good point, thanks for you reply.

The batery is brand new, had it load tested and it seems fine. Car still wont start even with two batteries connected in parallel.

Not sure if the starter is drawing too much current, would be a tough one to test without a new starter.

I must say that it doesn't sound like it is cranking slower than normal. If it cranked faster, im sure it would cure the issue though. Will check that out.

christopherdeanerogers

Good point. Ill check the idle air control valve tonight, not sure on its effect while cranking to start though?

Also, when cranking (attempting to start), I have tried moving the throttle around, but it doesn't affect it.

misterstyx69

iTrader: (142)

https://www.rx7club.com/canadian-for...in-t25-537488/
and https://www.rx7club.com/canadian-for...@15psi-697561/

I thought there would be more info in the threads but hey..it's a start..
a couple nice engine bay shots.

christopherdeanerogers

idle control valve is working fine.

Engine cranks at about 400-550rpm when cranking.

Any ideas of what the crank speed should be on an FD3S?
I notice with the freshly charged battery, the rpms get a bit higher during the crank when the engine finally fires.

christopherdeanerogers

Just a quick addition, the cranking rpms seem to slowly rise when trying to start the motor. They rise to about the 550rpm mark very briefly, at which time you can hear it wants to fire, but then the cranking rpm quickly drops back. If I keep the starter going it will do this cycle a few times before I stop cranking. This happens also when it actually starts, it just seems that the rpms get slightly higher than 550 for that brief moment, enough time for it to fire and start. At which time, the volts get above 12v.

Sgtblue

iTrader: (16)

I'm confused. First you said you didn't have a IAC, now you do. And how did you determine it's working properly?
Did you ever check compression as you said? The starting issue and the lack of stable idle may be unrelated. Have you downloaded a copy of the Factory Service Manual and tried trouble-shooting? If so, what did you try?

christopherdeanerogers

Apologies, I meant the throttle stop. I checked it and it seems to work fine. Important to note that the car runs fine at idle and normal operation. Agreed the two issues could well be unrelated.

I have gone through most of the electrical checks found in the manual, except testing of the coils. Might try that now, but I doubt they are the issue.

Tonight I have checked and cleaned all the starting system terminals I could find, the +- on the battery and starter, the engine ground and the alternator wire. Still the same issue. Haven't pulled apart the starter solenoid the see if the plates are clean.

Maybe the alternator or the regulator are not working properly at low rpm (400-550rpm)?


Any ideas about the correct cranking speed for a 13b?

christopherdeanerogers

Hi guys,

On the weekend I took the intake off and tested the coils. They all tested fine.

I also tested the spark leads and got high resistance along them, so they were replaced.
When I found this issue, I get very excited, hoping that I had found the issue. I put it all back together but the issue stil exists.

I tested each of the spark plugs by cranking the engine while holding the plug near the block. Looks like a pretty strong spark.

So, still at a loss as to the problem!!

christopherdeanerogers

Hi Guys,

Any idea of the votage while you crank your engine, prior to it firing?

I'm not sure if I should replace the alternator and regulator or if I should replace the ignitor.

misterstyx69

iTrader: (142)

you say it goes below 500-600 rpm..but what is your regular idle speed set at?

and if you are getting the engine to roll over at 550 RPM then that is one hell of a starting system.

(by the way the regulator is built in to the alternator)

christopherdeanerogers

Hi,

Thanks for your reply.

The engine cranks in the 400s rpm range and moves up in the 500s when it sounds like it is trying to fire.

Regular idle speed is around 800-900 rpm when warm.

misterstyx69

iTrader: (142)

Your increase in RPM when trying to start may be excessive fuel.
A flooded engine will allow it to spin faster because it fouls the plugs.But a good ignition can light it up.

I'd be posting this in the PFC section to see if it is a programming thing.
I had an Ecu that would allow me to start the car and then afterwards.NOPE..try and try.NOPE..not today.
Come back the next day and it would fire up.Start up and warm engine map were way off.

I'm not saying that is your problem,but It seems funny that your voltage dies off,and either your alternator can't power your car below the 5-600 range or your Ecu or sensors on your engine are not setup to keep the car from dying.

Yoloswag13b

im having this same problem just bought my car. single turbo convert. the car cranks and cranks and after a few tries starts right up after pumping the clutch and keeping key turned. sometimes needs a jump in addition to that. i was told it could be a grounding issue from the previous owner and tuner. or the size of the battery. i have 750 primaries and 2000 secondaries and a tiny race battery. but i found it strange i have the same idle problem, when i put the car in neutral and come to a stop. the idle dipped and engine died on me twice. going to see if a different battery resloves the issue

Yoloswag13b

check the starter relay. brought to irp they fixed in an hour. very happy car starts in one turn now.

trinirx

Have a similar problem, single turbo, pfc, bigger injectors etc but stock ignition system. the engine was recently rebuilt, starts fine once cold but as the engine warms up it would crank over slow and not start unless I put a battery charger on it at 12V high charge.

zunedg

hi guys, I have a problem with my RX 7 FD3S, when I give starter engine with ignition engine does not work, but when towing, the engine works more are working above 2000rpm when I leave the throttle the engine goes down, and the engine rolantim in the exhaust manifold is red-hot.

already checked all of devacuum call system tubing replaces the studies of solenoid valve (wastegate control and control turbo).

someone have idea ?

adey

Ditto, anyone else know the proper crank speed for the FD? Thanks!