Ignition Breakup after 5000 rpm
 

Hello everyone, I have an s4 rx7 with an s5 bridgeport turbo engine swap. I have an adaptronic Plug and Play ECU and 720cc primary and secondary injectors. I have a stock turbo on the car and its making around 10 lbs of boost but when im up in the higher rpm it stumbles and looses power for random short intervals. I have replaced my spark plugs, my leading ignition coil, and i have also set my timing by restabbing the cas and checking it with a timing light. The only problem is that when im checking the engine with a timing light, i lock the ignition timing in the ecu to 5,20. When i check the pulley for timing its almost 30 degrees advanced, but it idles very well and drives fine under 5000 rpm. Is there a possibility that my pulley is marked incorrectly or is something wrong with my CAS? Any input is appreciated.

Could be lots of things, but when was the last time you replaced your spark plug wires?

Plug wires are new, got some thick "racing" plug wires.

..and what plugs are you running in the engine?..

all 4 are NGK bur9eq

maybe you're just running too rich.

Post a thread in the Adaptronic section and include a map..that may be helpful.

an ignition amp is also very helpful, bridgeports in particular put a lot of strain on the ignition. they run excessively rich through all RPM and load ranges which tends to never give the plugs a change to clean themselves.

Remove the trailing plug wires, and do another pull. See if youre still experiencing breakup.

I have a wideband and it stays in the 13-14s under vaccum and around 10.5 under boost

.

.

Unplugged the trailing coil connector, my rpms didnt work, but i went out and did some pulls and the breakup is now even worse.

10.5 is pretty damn rich for the stock ignition to handle. plus not every wideband is exactly accurate.

i'd be willing to bet that if you took some fuel out in those 10.5 areas that it would go away.

or if you really want to maintain that additional safety buffer, install an ignition amp/CDI.

ill try leaning it out into the high 11's and ill see what happens

maybe high 11s up to 5psi and taper down to low 11s or 11.0 by 10psi. .5 AFR can make a big difference in spark blowout.

i will say higher voltage output from the coils is always good to have though, it gives you a bigger window than that 1-1.5AFR you have from ignition rich breakup to potentially blowing an engine.

Tach works off of the trailing coil, so the tach not working is normal.

try to find TDC on your engine. theres a few ways to ball park it.

This only works on an S5: Take out the spark plugs on your rear rotor housing. Take a mirror and look into the holes. position the apex seal in the center of the top hole and mark the pulley. Then rotate the engine to position the apex seal into the bottom hole. Mark the pulley.

The center of these two marks is ~TDC. Your 5* mark should be somewhere near there. If you want to find 5ATDC, measure the circumference of the pulley, divide it by 360, and multiply it by 5. That would be the distance the 5* mark should be from TDC.


Another way is to put 2 long alan wrenches that are the same length into the front plug holes so that they touch the rotor face. The wrench you use for the trailing hole will need to be really skinny because the trailing hole is small. While applying pressure, rotate the engine until the alans are even. this should be ~TDC.

If your pulley is ok, you probably need to adjust your timing maps.

that method doesn't work for finding proper TDC and it should never be used to try to accurately time a turbo engine. the spark plugs are not asymmetrically placed in the engine. in fact i wish that method was never even put up, because some people have taken it as true.


the ONLY accurate way to time the engine once it is assembled is to use a known good timing hub. the other methods will give you an idea that your timing hub isn't way off, but also won't tell you if you are close or even remotely accurate.

however almost none of that matters anyways, because advanced timing doesn't result in a sputter, usually by the time you can feel an overly advanced timing curve in a rotary engine it already hasn't survived.

S5 engine spark plugs are asymmetrical, S4 engines are not. And i never said accurate, i said ball park to check the timing marks.

neither s4 or s5 are really that close, iirc using that method could only get you within about 20 degrees of true TDC, which is actually quite a ways off and unlikely any FC pulley is off further since the bolt patterns for the pulley to hub are keyed, but even those hubs to pulley matches can be problematic since they had slight changes over the years.

Id say more like within 5 degree. This has already been covered to death. S4 turbo is the only odd man out. It has the leading hole raised.

And if youre saying a 30 degree timing advance at high rpm/in boost wont cause ignition breakup, well.........

https://cimg0.ibsrv.net/gimg/www.rx7...f6b4711a05.jpg

i'm not going to argue it further, if you like to place a rotor on the eshaft and perform the test with the engine apart you will see exactly what i mean. the problem you aren't realizing is that neither the lead or trailing plug is centralized in the housing.

Look guy, heres a pic of an S4 housing. They dropped the leading ~.3 of an inch on the S5 housings putting TDC right in the center of the plug holes. I wish I had a clear pic of the inside of an S5 housing so i can show you.

https://cimg0.ibsrv.net/gimg/www.rx7...2522035335.jpg

S5 rotor housing. Center of the two holes are 4.2mm from TDC which translates to about 2 or 3 degrees on the pulley. Goodnight.

https://cimg6.ibsrv.net/gimg/www.rx7...dc29bc4eb8.png

and im telling you they are NOT perpendicular to true TDC, but you're the one who blew his engine and perpetuating problems with these engines and particular processes that are not proper.