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View Full Version : RB25 (S1) Cranks but wont fire


skazat
10-10-2011, 08:28 PM
Hey guys I need some help troubleshooting an issue with my RB25.
Long story short my RB25 wont fire up, it cranks but doesnt actually fire up. Its getting fuel but I dont think its getting spark. If you want more info read the info below.

Let me give you some background first. Ive been working on this car for a bit now but ever since school has started my progress has come to a stand still. Its a pretty much stock RB25 swapped into a s14. Its running on an AEM EMS and has been converted to speed density (I got rid of the maf and went with MAP and IAT sensors). I had it running before and it would always fire right up, the reason I havent driven it is because I still need to tune it but havent had the time with school having a hold on my balls.

The last thing I did to the car was pull the passenger side valve cover off to weld a bung for an evac set up. I went to turn it on the other day to move it and it wont fire up. It will sit there and crank but wont fire. I checked for fuel and its got pressure and everything, I hooked up a timing light to a spark plug wire i have in between the coil and plug that I used for setting base timing (I left it in there so I can use it as a pick up point when I dyno it) and its not lighting the timing light which leads me to believe its not getting spark.

It was raining the last day I was out where the car was so I could diagnose past that. My next step is to hook up my laptop to the EMS and see what the Stat Sync is saying to at least make sure the CAS is reading. Other than that I dont know what else might have caused this issue.

I just cant believe after the motor sitting on a bench for almost a year and then firing up and running fine everytime i fired it up for a month and now its got an issue. Sorry for the essay but thanks if you read all this.

IBoughtAS13
10-10-2011, 08:33 PM
Use your AEM and see the issue. You have to check the cylinder to see if you are getting fuel
In the cylinders. Fuel pressure does not mean you are getting fuel in the cylinders, that is what pulsing is for.

Does the AEM read the CAS?

skazat
10-10-2011, 09:49 PM
I didnt get alot of time for diagnosis so next time I get a chance to I will be checking to make sure the fuel is getting into the cylinders and that the CAS is registering with the AEM, I believe the the Stat Sync will be able to tell me that. I know its definitely getting fuel into the rail and Id hope theres nothing wrong with the injectors since I just got them cleaned out before I fired up the car.

Actually I was forced to because when I went to fire up the motor for the first time since I got it all the injectors were stuck shut. After getting them cleaned the motor fired right up. So Im really hoping/doubting the injectors especially since Im not getting spark.

Im just wondering if the CAS is registering and it IS getting fuel into the cylinder why would it not be sparking? Could something have gone bad? Is there fuse somewhere that I might have to check? I just want to get some suggestions before I go out there again.

Brok3n_RB25
10-11-2011, 10:22 AM
Did you take off the coilpack ground that goes to the valve cover? If you didn't put that back on, it could be your issue.

skazat
10-11-2011, 01:54 PM
You mean the one ground on the back of the coil pack harness? Its just a single ground that bolts to the head, right? I didnt think that there were grounds that were actually on the valve cover.

Brok3n_RB25
10-11-2011, 03:01 PM
I believe mine is grounded to the head. I can double check in a little bit when I get home. That little guy could do it. Also, just check grounds in general. They can cause a lot of things to go wrong.

skazat
10-12-2011, 06:37 PM
hah i dont know what went wrong but i went to hook it up the other day and was double checking fuses and when i pulled one out and put it back in i heard an audible click and saw the the fuel line tense up from pressure which wasnt happening before. went to fire it up and there she purred right up! Im excited to back to where I was lol. Now I need to get back to tuning it. Hopefully some extra time comes along where I can get it up on the dyno.