I swapped out my timed out engine for a factory new engine last week. I added fluids, dry-cranked the engine until I saw oil pressure come up (30+ psi), and then tried to start it. The behavior is that it fires and runs for about one to two seconds, and then dies. It runs right up to 2000 rpm, and then quickly tapers off and dies. I have tried increasing the idle speed which makes it run at higher rpm, but it still dies.
I examined all of the ECU data and trips -- fuel pressure, oil pressure, lean trip, ... nothing appears to have caused an ECU trip. I have 3.4 bar of fuel pressure and above 30 psi oil pressure.
I installed new throttle body rubbers and ensured that the clamps are snug.
The one thing I remember before swapping engines is that the car at the end of my last two-day test in March began to have a similar issue where it would start and then die. I tried increasing the idle speed, but this did not seem to have an effect. On the last session, I had to use throttle to keep the idle going initially, and then when I came in the engine died when I got off the throttle. This is a new thing that never occurred before this last test.
Any ideas or things I should look at? Maybe I missed a connection but I don't think I did. The brand new engine seems to want to run, at least initially. It is not running rough, just dying quickly.
@davidf Hi David -- that's quite a puzzle. Can you see the TPS % via data log? Is it above zero when the engine dies?
Thanks John.
TPS stays the same -- 4.1%.
Some new info ... I put a zip tie end between the throttle and idle adjustment screw. This makes the engine run at higher rpm initially and the TPS is 5.7%, but still dies after one second. Then I wedged the end of a small flat head screwdriver and this gets the engine to continue to run at high rpm -- about 3500. As long as the rpm is kept high, the engine does not die. This appears to be the same condition that I left the track last month, so I now do not suspect that I forgot to connect something, although I don't want to eliminate any possibility.
@davidf The engine seems to be behaving as if it doesn't know it's idling, as the ECU makes extra effort to keep an idling engine running, using spark advance since it doesn't have control of the throttle as it would with a DBW setup. So that could mean the ECU doesn't know the engine RPM somehow? Does the log with the TPS % show engine RPM? Is it (mostly) accurate?
In fact, if you can have a look at spark advance as well in the log. You should see it changing fairly rapidly as the RPM dies.
rpm looks right in the data. Thanks, I will look at the spark advance. I didn't know it logged that.
@davidf, I am leaning toward a fuel injection issue. Here are my thoughts. If it was doing it with your last engine then it is obviously one of the parts that wasn't changed. When you start the engine and it dies, will it start again if you try right away or do you have to cycle the master switch first before it will start? When you first power the master switch it puts the ECU in "Start mode" which provides more fuel for a short period of time. What could potentially be happening is that the engine runs momentarily with the extra fuel from the "Start Mode" and then dies when the "start mode" shuts off. If you have extra fuel injectors I would try swapping them out, or if you don't I would recommend having them flow tested.
Hopefully @RLM-Dan will comment also...
When you start the engine and it dies, will it start again if you try right away or do you have to cycle the master switch first before it will start?
It will start right away. I don't have to cycle the master switch to get it to fire multiple times.
I agree with Charley and had the same thought. Sounds like the fuel at idle is insufficient.
@davidf - I installed a brand new engine from Radical late last year as well... and had EXACTLY this issue. After many, many attempts to increase idle speed and modulate the throttle to try and get the engine to run 'near' idle, we decided that we would put some more fuel in the fuel cell to make sure there was enough. Please not that the engine was not 'tripping' on low fuel pressure, but there was something funny happening with fuel/fuel pick up. I think to begin with we had only put about 7 litres into the tank. After we put the rest of a 20 litre drum in (making the total 20 litres) the car started and ran fine immedialtely....
I can't say you have that same problem, but the symptoms you are describing are identical.
@davidf @rjbender @joep @charleyhradicalsportscarregistry-com
I don't see how a low fuel situation would prevent a car from idling, but would allow it to run fine at higher RPM.
Anyway... some other interesting information: my car is less tolerant of low fuel levels since I put in a new fuel bladder a couple of years ago. I have to put in fuel very slowly too, to the point where I changed the ATL dry break system back over to an ordinary fuel cap.
My theory in my case is that the foam in the bladder is "slow". Slow to absorb gasoline, and slow to release it.
So: do you (David or Rod) have new or fairly new fuel bladders?
@parsonsj I wasn't necessarily thinking low fuel level. Perhaps the map needs to be adjusted (made fatter) in the area of the idle post cranking.
@joep Gotcha. I keep thinking this would be a lot easier to resolve if we had proper engine data -- like, say from a MoTeC ECU, or even an open Life ECU. 🙂
@parsonsj - G'day John, No - the fuel cell bladder in my car is the original from October 2015 build (although the car did sit in my garage for nearly 3 years without use....)
I don't have any issues with having to 'slowly fill' my bladder and can put 20 litres into the car in about 5 seconds.
Here's the adaptor I made for the dry break fuel assembly that allows me to use smaller fuel churns than the huge ATL churn that comes standard with the car... this one is 12 litres, but I now use a 20 litre version of the same brand fuel churn (from RISK Racing - motorcycle supplier) with my new adaptor. Its much much easier to use on my own than that bloody great thing from ATL...
... happy to supply drawings for the adaptor for anyone who is interested.
Thanks everyone for your thoughtful posts.
@rjbender -- I put 6 gallons of fuel in the cell. When I did a purge the flow was strong.
@parsonsj -- the car and fuel bladder are new. Car built in 2021.
Some new information. The engine builder at Spring Mountain suggested the following procedure to reset the idle screw, which I followed, however no improvement:
Try backing the idle screw all the way out until it no longer touches the stop. Then set the TPS with the stop backed off to between 2.3 and 2.5. Then using the idle screw, open the throttle bodies until the TPS reads between 4.0 and 4.5. Try to start the car with out applying any additional throttle.
I am coordinating with Spring Mountain to determine what exactly to send them for my engine refresh. I will send them my throttle body assembly, ECU, perhaps coil and wires. They are willing to swap these in when they dyno my refreshed engine to try to determine the problem.
More new information: After the idle screw reset above, I ran the engine at 3000 rpm for a little longer, and then let it back down to idle. It did idle at 1700 rpm for about 10 seconds, however not well. It sounded very ragged like it was running on 3 cylinders. Similarly, it runs very rough at 3000 to 3500 rpm.
