car cranks really slow..

Rotary#10 · 04-16-2009, 11:57 PM

well one problem after another on my daily driven 7...
its a 91 n/a FC... it cranks really slow...
battery is over 12.4 volts
starter is good had it tested at autozone
plugs are good, I have spark
I have fuel and air of course..

any ideas ? ign switch?

My5ABaby · 04-17-2009, 06:57 AM

What's the voltage while cranking?

Max777 · 04-17-2009, 11:04 AM

Do you have a "DVOM" (Digital Voltage/Ohm Meter) available to diagnose your problem?

Get a Haynes Manual for the RX-7, as well as take a look at buying a Factory Service manual, if this is your daily driver, the book will SAVE you money in the long run, so it's a heck on an investment. I think Racing Beat might still have a paper version in stock, or if you could just go here:

http://www.rx7city.com/techconnect.htm

PS: Even with quite a few knowledgeable people on here, it's still better to look at the factory service manual first to avoid wasting time on simple problems.

vex · 04-17-2009, 12:25 PM

Voltage Drop test. It could be anything from a weak battery, to a bad voltage drop across the starter (and everything in between). Break out your Voltmeter and start testing.

Whizbang · 04-21-2009, 01:37 AM

what kind of battery. hold old is said battery. what is the CCA rating?

rx4ur7 · 04-21-2009, 02:42 PM

Get the book and DVOM.
Check battery connections and all grounds. If good test battery.

TehMonkay · 04-23-2009, 09:32 PM

yeah check the resistance on the wires going to the starter, perhaps try to clean them where they attatch to the starter as well.

Rx-7fetish · 04-24-2009, 11:32 AM

Quote:

Originally Posted by Gravity Fed

what kind of battery. hold old is said battery. what is the CCA rating?

I believe GravityFed meant how old, and ditto on asking the age and cold cranking amperage.....

Rotary#10 · 04-24-2009, 07:52 PM

hey ya'll i pulled the plug on my car for a while... i figured if its going to be down I'll get the injectors cleaned.. so i'll post an update bout when i put things back together...

Rotary#10 · 05-07-2009, 10:57 AM

Hey ya'll this is something that i figured out last night.... its highly possible that the plugs i put in a san jose. Fouled up on the trailing side, the plugs i pulled on the trail side of both rotors had oil and ash or (carbon?) on them when i pulled them... i tested all the plugs and the trailing had weak spark. compared to the leading which had stronger spark.. speaking from visually seeing the spark itself.
Do you think that what happened? I redid some grounds and added some too..

Rotary#10 · 05-07-2009, 10:59 AM

Quote:

Originally Posted by My5ABaby

What's the voltage while cranking?

Cold cranking amp 640. Do you think I need something higher?

My5ABaby · 05-07-2009, 11:30 AM

Quote:

Originally Posted by Rotary#10

Cold cranking amp 640. Do you think I need something higher?

Volts != amps.

Rotary#10 · 05-07-2009, 04:53 PM

Quote:

Originally Posted by My5ABaby

Volts != amps.

thanks but everytime i crank the car over and over it sounds like it getting slower, i rechanged that same battery over 2 hrs ago and it still cranks really slow... its not my grounds, I cleaned them and checked them too, even added a few. any recommondations on a new battery ? brand ? cranking amps? price ? etc

mazda master tech · 05-07-2009, 09:35 PM

[QUOTE=Rotary#10;82910]well one problem after another on my daily driven 7...
its a 91 n/a FC... it cranks really slow...
battery is over 12.4 volts
starter is good had it tested at autozone
plugs are good, I have spark
I have fuel and air of course..

any ideas ? ign switch?[/QUOtE

mazda master tech · 05-07-2009, 09:38 PM

Look at your cables or manual trans could be your throw out bearing

04-17-2009, 06:57 AM	#2
My5ABaby Sigh..... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (6) Posts: 2,377 Rep Power: 19	What's the voltage while cranking? __________________ 1986 Sport: 132k miles, 5A (Sapphire Blue Metallic), Tokico Blues, Racing Beat Springs, Custom LED tailights (only S4 LED tails in the world), SSR Mark II, Racing Beat exhaust, S5 black interior, Rotary Resurrection rebuild at 120k miles Community Service Manual RotorWiki "Imagination costs nothing; we could build square locomotives or fly to Mars" - Felix Wankel Yesterday is history, tomorrow is a mystery, but today is a gift. That is why it is called the "present."

04-17-2009, 11:04 AM	#3
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Do you have a "DVOM" (Digital Voltage/Ohm Meter) available to diagnose your problem? Get a Haynes Manual for the RX-7, as well as take a look at buying a Factory Service manual, if this is your daily driver, the book will SAVE you money in the long run, so it's a heck on an investment. I think Racing Beat might still have a paper version in stock, or if you could just go here: http://www.rx7city.com/techconnect.htm PS: Even with quite a few knowledgeable people on here, it's still better to look at the factory service manual first to avoid wasting time on simple problems. __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 04-17-2009 at 11:10 AM..

04-17-2009, 12:25 PM	#4
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. iTrader: (6) Posts: 2,113 Rep Power: 19	Voltage Drop test. It could be anything from a weak battery, to a bad voltage drop across the starter (and everything in between). Break out your Voltmeter and start testing. __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

04-21-2009, 01:37 AM	#5
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp iTrader: (5) Posts: 3,190 Rep Power: 20	what kind of battery. hold old is said battery. what is the CCA rating? __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

04-23-2009, 09:32 PM	#7
TehMonkay Rotary Fanatic Join Date: Apr 2008 Location: Louisville, KY iTrader: (0) Posts: 302 Rep Power: 17	yeah check the resistance on the wires going to the starter, perhaps try to clean them where they attatch to the starter as well. __________________ My car blows up everytime I start it, it's rotary

04-16-2009, 11:57 PM	#1
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland iTrader: (1) Posts: 219 Rep Power: 17	car cranks really slow.. well one problem after another on my daily driven 7... its a 91 n/a FC... it cranks really slow... battery is over 12.4 volts starter is good had it tested at autozone plugs are good, I have spark I have fuel and air of course.. any ideas ? ign switch? __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

04-21-2009, 02:42 PM	#6
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson iTrader: (0) Posts: 231 Rep Power: 17	Get the book and DVOM. Check battery connections and all grounds. If good test battery.

04-24-2009, 07:52 PM	#9
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland iTrader: (1) Posts: 219 Rep Power: 17	hey ya'll i pulled the plug on my car for a while... i figured if its going to be down I'll get the injectors cleaned.. so i'll post an update bout when i put things back together... __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

05-07-2009, 10:57 AM	#10
Rotary#10 Rotorhead Join Date: Sep 2008 Location: "the town " Oakland iTrader: (1) Posts: 219 Rep Power: 17	Hey ya'll this is something that i figured out last night.... its highly possible that the plugs i put in a san jose. Fouled up on the trailing side, the plugs i pulled on the trail side of both rotors had oil and ash or (carbon?) on them when i pulled them... i tested all the plugs and the trailing had weak spark. compared to the leading which had stronger spark.. speaking from visually seeing the spark itself. Do you think that what happened? I redid some grounds and added some too.. __________________ Currently running: 90 GTUs converted to S5 TurboII. Track car. 90 N/A GTUs.. Running project car 89 N/A GTUs in Black #2 10/6/18 Blown coolant seal undergoing rebuild and restomod.

05-07-2009, 09:35 PM	#14
mazda master tech Gear Head Join Date: Nov 2008 Location: Birmingham Alabama iTrader: (0) Posts: 8 Rep Power: 0	[QUOTE=Rotary#10;82910]well one problem after another on my daily driven 7... its a 91 n/a FC... it cranks really slow... battery is over 12.4 volts starter is good had it tested at autozone plugs are good, I have spark I have fuel and air of course.. any ideas ? ign switch?[/QUOtE Last edited by mazda master tech; 05-07-2009 at 09:36 PM.. Reason: woops

05-07-2009, 09:38 PM	#15
mazda master tech Gear Head Join Date: Nov 2008 Location: Birmingham Alabama iTrader: (0) Posts: 8 Rep Power: 0	Look at your cables or manual trans could be your throw out bearing