Fresh rebuild wont start!!
10-13-10, 09:06 PM
#1
Fresh rebuild wont start!!
So i just put in my newly rebuilt motor,without the rats nest. I didn't plan on removing the rats nest but it waqs damaged when installing the negine so i decided i might as well remove it know. i used the rotary resurection instructions for my s4 NA. i didn't have the block off plates so i installed the egr valve with a nipple on the end and did not remove the BAC valve or coldstart syste, or ACV. now i was unable to get it to start after a little bit i double checked fuel and spark and it was getting both. I decided to try and pull start it and it worked! the engine started and ran but won't run under 2800 rpm so i pulled it into the garage to check for vacum leaks and i still havn't found any so does anyone have any advice as to why it won't run under 2800 rpm or documentation of every vacum line to check.
Thanks ahead of time
-Bobby
Thanks ahead of time
-Bobby
10-13-10, 09:15 PM
#2
Try stabbing the CAS again, and see if a little oil to build compression will help things along. You've probably got a vacuum leak somewhere. Remember, not only vacuum leaks, but UNMETERED air as well can screw things up. That's anything between the MAF and TB.
10-15-10, 03:59 PM
#5
well i did reinstall the CAS correctly by aligning yellow mark to pin and the pin on collar of CAS with the mark on the CAS housing but it still wont idle. i can only get it to start by bumb starting it or pulling it around the block. it starts relatively easily using those methods. however once it starts it still refuses to idle as soon as it gets under like 1800 rpms now it will die. its rebuilt with all knew seals s5 rotors and large streetport so i have the idle speed screw all the way up and the a/f all the way rich and it still won't idle. so anymore ideas?
10-15-10, 04:07 PM
#6
three spinning triangles
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i remember reading that rebuilt engines can also have low compression thus making them harder to start.
read this... this will help explain.
http://www.rotaryresurrection.com/2n...p_breakin.html
read this... this will help explain.
http://www.rotaryresurrection.com/2n...p_breakin.html
10-15-10, 05:06 PM
#7
well i did reinstall the CAS correctly by aligning yellow mark to pin and the pin on collar of CAS with the mark on the CAS housing but it still wont idle. i can only get it to start by bumb starting it or pulling it around the block. it starts relatively easily using those methods. however once it starts it still refuses to idle as soon as it gets under like 1800 rpms now it will die. its rebuilt with all knew seals s5 rotors and large streetport so i have the idle speed screw all the way up and the a/f all the way rich and it still won't idle. so anymore ideas?
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10-15-10, 05:32 PM
#8
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Rebuilds will indeed have terrible compression if new hard seals are used and will be very hard to start for a while. You can do what I did and add maybe a tablespoon of motor oil to each leading sparkplug hole, then start it. Keep in mind if you do this, it's going to smoke like a bitch.
As for idle, there are a number of ways to locate vac leaks, a little beit of searching will bring you all of them. When I rebuilt mine, I did a poor job with the LIM and had to take it apart, put a dab of RTV on the gaskets, then all was better. My favorite way of locating bad vac leaks is to take a few foot length of vac tubing, stick one end in my ear and probe around the engine with the other end while its running and listen for hissing.
And finally, if you have the car running at all then the CAS is more than likely stabbed correctly, but you'll still want to set the timing properly with a timing light.
10-15-10, 08:41 PM
#11
^Scrims is right. Finding vacuum leaks can be a bitch, but you can use a can of brake cleaner with it running to find it. It'll sound different when it hits the leak. Here's some crazy food for thought: My rebuild was HARD to start as well. It finally started after lots of cranking and de-flooding, schmoozing, etc. It took me a long damn time to figure it out, but I realized that I installed the CAS drive gear backwards. Don't know how I did that. I know (and knew then, too) how it's supposed to go on. I pulled the front cover and saw that pretty much right away. I flipped it, reinstalled the front cover, re-stabbed the CAS, and it fired up first try. It may not be your situation though, but worth a thought 
10-16-10, 01:25 AM
#12
my bad here is the pic,
Anyway the plan is to take of the UIM tomorow and double check all the vacum nipples then go ape **** with RTV. is there anyway to see if you have proper vacum pressure? like a gauge or something. also i was wondering if a injector lead having a short in it would cause the above symptoms?
Anyway the plan is to take of the UIM tomorow and double check all the vacum nipples then go ape **** with RTV. is there anyway to see if you have proper vacum pressure? like a gauge or something. also i was wondering if a injector lead having a short in it would cause the above symptoms?
10-16-10, 01:44 AM
#13
^Scrims is right. Finding vacuum leaks can be a bitch, but you can use a can of brake cleaner with it running to find it. It'll sound different when it hits the leak. Here's some crazy food for thought: My rebuild was HARD to start as well. It finally started after lots of cranking and de-flooding, schmoozing, etc. It took me a long damn time to figure it out, but I realized that I installed the CAS drive gear backwards. Don't know how I did that. I know (and knew then, too) how it's supposed to go on. I pulled the front cover and saw that pretty much right away. I flipped it, reinstalled the front cover, re-stabbed the CAS, and it fired up first try. It may not be your situation though, but worth a thought
10-16-10, 03:39 AM
#14
If it can't idle below 1800 it would have to be a huge vaccum leak. I would think the cas is stabbed wrong or something else major. Spark plug wires all good? good housings used?
10-17-10, 12:47 PM
#18
What should it be idling at if the idle speed screw is maxed out? Cause it is idling at like 1300 which according to rotary resurrection is fine for a fresh rebuild however if I completely let off the gas it dies. So could it be my tps or something?
10-17-10, 02:44 PM
#19
What should it be idling at if the idle speed screw is maxed out? Cause it is idling at like 1300 which according to rotary resurrection is fine for a fresh rebuild however if I completely let off the gas it dies. So could it be my tps or something?
10-17-10, 07:47 PM
#20
Well, what's confusing is that you say it won't idle below a certain rpm, but that's indicitive of a vacuum leak. The problem is that your car won't stay running below a certain rpm, it's not idling at all. That's probably not a vacuum leak issue now that I think of it. Remove L1 and T1 plug wires at the coils and see if it runs the same, then try it again with L2 and T2. That way we can see if it's running on one rotor. You could have a stuck seal that just needs to free itself up.