SR20VE serious kickback issue
First of all, this will be a long post, I hope someone has the patience to read it until the end.
I am a very long time follower of this forum and I have learned a lot in here, but I have not posted before.
I live in Ankara, Turkey and I have the one and only 00' Primera P11-144 Hyper CVT M6 with an SR20VE in Turkey.
It took 1,5 years for me to gather all parts and another 6 months to have the job done by the most reputable Nissan shop here in Turkey.
The shop is specialized in building race engines for drag / drift cars and they have a 750 bhp CA18DET in their S13. They have also built many RB26's and 2JZ 's. They are very capable of building turbo engines but this is the first time they have built an all motor SR20VE, since we do not have SR20VE 's here in Turkey. The specs of the engine are listed below :
SR20VE head on EUDM Roller Rocker block
-Lightly skimmed head
-Supertech +1mm intake valves
-Supertech std exhaust valves
-Supertech springs (93 lbs) and retainers
-Kelford 184-D cams (20V/N1 hybrid)
-Tomei Cam gear
-Bosch EV14 550cc injectors
-VAG coil on plug
-SR20VE 20V CAS
-Spark EMS standalone ECU (an ECU designed and built by a Turkish guy and there are a few hundred people using this ECU for their engine builds. As far as I know, the ECU has been derived from a VEMS ECU, the software seems very similar too.)
-MAF Delete / Bosch MAP
-Custom intake manifold + Blitz SUS Power air filter
-75mm RMR throttle body
-The bottom side is as follows :
-SR20DE 4CW crankshaft
-Manley H-Beam rods
-CP 87mm 12.5:1 pistons
-Mazworx 87,5mm SR20VET headgasket
-Mazworx mechanical timing chain tensioner
-New OEM water pump, oil pump, crank pulley, timing chain and gaskets.
-ASP 4-1 3” header
-Stainless 3” exhaust system with 2 Vibrant Ultra Quiet resonators and 1 Dynomax VT muffler (still very loud)
-PLX Wideband (Bosch 4.9) + EGT
-Speedhut gauges for Water temp, Oil pres. and trans temp.
-Improved Racing oil cooler
-Improved Racing trans cooler with thermostat and fan
I had the engine built about 3 weeks ago and I am still using the CVT transmission and it is not as bad as you think it is. I always have the chance to convert to manual. I may have done 400 - 500 miles since the build and the shop wants me to drive like 1250 - 1500 miles for breaking in the engine. Right now I have igniton cut at 5k rpms and the intake cam engages at 4.5 k for just 500 rpms
Even though everything looks good on paper, the thing is that, I want to pour gas on the car and burn it down to watch it explode into fireballs............because,
The car has very very very serious starter kickback issue. It ate the original starter, a hybrid one with a more powerful motor (2 times) and today, a frankestein one from a 3 liter diesel engine. It broke the bendix 3 times, the reduction gear twice and broke the nose cone once. We have even added a brace to the end of the starter to fasten it to the engine block.
Cylinder compression test was over 300 psi on each cylinder (the gauge only goes to 300 psi) and the first diagnosis was that the original starter cannot cope with the compression since the starter for the CVT motor has lower rpm and less torque than the manual version. The compression shall be a bit higher than 12.5:1 since the head has been lightly skimmed.
When we try to start the car, the engine turns then stops for a second, then keeps on turning, then stops again, and if you are lucky, it starts. It also pops and bangs like crazy (we sometimes have explosions from the intake manifold and exhaust during cranking) Once it starts, it has a smooth (but a bit on the high side like 1200 rpms) idle and runs fine. During cruising, the AFR is between 14.5 - 15. But generally the case is, especially if it is a bit cold outside or if the engine has not been run for more than 12 hours, it does not start, it pops, bangs and breaks the starter because of kickback. The AFR goes lean after a few cranks and I have to step on the gas pedal to get it to start. If I was lucky and could start the engine, I can start it again within a few hours time, before the engine completely cools down, but usually by having to step on the gas pedal.
I run 15 - 20 pct ethanol over 95 octane gas (it translates to 91 octane for US guys) or 97 octane (93 for US) whenever I can find it. If I don't add ethanol, it pings. The timing has been retarted both mechanically and by the ECU and the timing advance has been pulled down to 0 degrees during cranking. I have been told that the ECU has been programmed to crank the engine for 2 full cycles without spark then ignition is activated at the 3rd cycle.
I have read about many many builds on this site and sr20forum but no one has had such problem, so I am not sure what is going on.
I am sure that the guys at the shop did not degree the cams with a degree wheel, but they say that they have triple checked the cam adjustment, and the car does not want to start even if they retard the cams by the cam gear.
The battery is new and has 800 CCA, we have upgraded the cable to the starter with a 0 AWG cable. We have checked the grounds as well.
I am about to lose my mind and I cannot think of a solution. I am very depressed to see that after all that cash and time spent, I am left with a piece of garbage lying in front of the house.
I hope someone can guide me since I am out of ideas...
Thank you in advance.
**Official Chat Killer**
Check the base ignition timing. If you have too much advance with a lot of compression you can actually get strong combustion before TDC which will try to rotate the engine backwards. Try either retarding the cranking ignition timing in the map or retard the distributor.
G20 Senior Member
I would also get a machinist to find the exact degree of TDC from the first piston, and make sure your cams are dialed into the specs provided Kelford. This is specific to the Kelford 184-D cams (20V/N1 hybrid) you mentioned in your post.
Couldn't agree with Snickers anymore, symptoms you're experiencing are timing related.
G20 Junior Member
+2 on the timing. Is the compression still high when it's warm? Any liquids leaking into the cylinders? Maybe put in some recirculating block heaters for coolant and oil to avoid the cold start.
Thank you all for your comments. I also believe that this is a timing issue but we have not been able to find the exact cause for it.
My tuner has retarded the timing on the map before but it made little difference, and retarding the CAS did not do so much as well.
The car starts better once it is warmed up, so it is a cold start issue.
Do you think that cams that are not properly degreed may cause this much of an ignition advance ? I mean the car runs quite well if I am able to start it, so I guess the degree may be off but not to the extent to make the car run sloppy. This is just my idea, please tell me if I'm right or not.
I think high idle issue is related to the timing as well, because we have not been able to correct it via IACV regardless of how much we lower its duty. The idle screw on the IACV is tightened completely, too. The throttle body is not cracked open as well.
So, it seems that the ignition timing reading on the tuner software may be less than the actual timing of the engine itself, so it shall be checked with a timing light. I think it has not been checked since the COP harness does not have a provision for timing light.
Can it also be that the ECU has a false CAS reading ? Will I be able to check it with a timing light ?
G20 Senior Member
Originally Posted by HolyLight
I do, get your mechanical timing down first before trying to tune. Otherwise it renders your ECU tune pretty much useless. Because you're trying to compensate fuel and ignition maps/trims to correct a bigger issue. I'm not trying to jump to assumptions here, and it looks like with the assembly of the top end has the exhaust cam zero'd out.
Quick way to check would be to pop the valve cover and see if the cams were even degreed to their specs at all. Sometimes that is not even accurate enough. You often want to get a degree wheel on the front crank pulley, and measure EXACTLY where TDC is at based off cylinder 1. There is a very effective way to do that with a dial gauge/indicator. Use THAT position to degree your cams, when there is no slack on the chain. That will be the closest way to make sure you are on the money.
Start this video at 20 minutes, this video has some great info, same principles apply.
G20 Senior Member
I guess what I'm trying to say, is if your shop simply relied upon the manufacture's specs to dial the cams, and didn't go through a full thorough inspection of the cam timing based off actual TDC, I wouldn't be surprised if the idle and RPM band were a bit choppy. You have a VERY modified setup, where even deck heights of the head and short block could cause variations between how the cams are degreed on a completely bone stock VE (which yours is clearly not).
I'm not saying I'm right here, just trying to throw a suggestion for all of the information you've mentioned and noted thus far.
Thank you for the feedback. Sadly shops around here do not have the habit of using cam degree wheels, but they rely on their "experience" with motors. That is why I am in this position now.
I will get them to use a cam degree wheel and once we have the cams properly degreed, we will investigate further.
G20 Senior Member
make sure the trigger wheel in the CAS is for your EMS
this was an issue with the megasquirts ( now fixed ) and believe AEMs as well
i have currently v3 184c's in my ve, which actually have the same low lobes as the 184d's. amidst a few changes to the motor, my tuner has played with the both cam gears, had several different settings, but never had any issue at all like you have had. i'm using a motorbike battery, and nearly pegging the compression tester on premium unleaded.it idles smooth @900rpm, as has a lovely little pop/crackle when coming off full throttle.
i too think the issue is timing related, and maybe tune (injector latency) and fuel pressure worth looking at too. i know its an expensive option, but a standalone ecu might fix all your issues, including the iacv.
This is also how I am expecting the motor to behave as well... I will have the shop re-degree the cams and we will investigate further. I am still using the OEM Nissan CAS disc with 360 slots, maybe that is why I have erratic ignition - even though the engineer of the standalone says the ECU supports OEM Nissan CAS disc. This issue I am having seems to be a lot more than a few degrees of erratic timing, I think there is more going on. We will see.
Originally Posted by sss4me
So what is your "mechanical" base ignition timing as of now ? 5 degrees ? I wish I could also find an ignition and fuel map from a motor like yours to compare with mine.
i used to run nismotronic in a sr20de ecu with its factory setting of 15 deg. the standard sr20ve ecu is 5deg. now i run a haltec standalone (ps1000)
Originally Posted by HolyLight