BlackFox

First of, I started this topic in this section because I hope to receive more response here then in the S2000 section. Also, I believe this isn't an S2000 specific issue.

Just swapped my engine myself with the help of my brother after dropping a valve.

Engine and cylinderhead is new (well, used, but should be ok), everything else (electronics, intake, exhaust, ...) is from the old engine.

Engine will start and idle, but as soon as I hit the throttle and release it, it will bog down and stall.
Startup again is also an issue, usually needs a little throttle. Then it won't idle and stall again as soon as I release the throttle.

Keeping the revs up is not a problem, and after a while it will idle nicely.. Untill I hit the throttle and it stalls again.

Already cleaned IACV, reset the ECM and cleaned the MAP contacts and used a tie wrap to keep it in place. Nothing seems to help.

Spark plugs are brand new, airfilter is a recent K&N, no CEL and no errors if I read it out with an OBDII app.

Possible timing issues or valve adjustment issues? The previous owner only used this engine briefly for some track days and then swapped it out for a Toda engine. It did had ITB's and possibly a dfferent head. So I don't know if the timing has been touched.
However all the electronics and intake are now from my old standard engine...

When cold, it won't stall, probably because the revs are higher. It will make a popping sound through the exhaust whilst idling, but only when cold.

I can drive it, but feels like it's lacking power a little, didn't go past 4-5000rpm though. It will bog if the rpm's are to low, like <2500rpm. And of course stall eventually.

I've also performed a check that was stated in the workshop manual (page 11-91). If the car stalls when you put your fingers in the 2 holes of the throttlebody, you should replace the IACV.

Mine does stall when I do that, so that would mean my IACV is bad? Any other way to check?
If I disconnect the IACV connector, the engine will still keep idling, but as soon as I hit the throttle, it will start to fluctuate. Won't stall however.
When I reconnect the IACV, the engine will stall.


Probably also worth mentioning: we couldn't reach 2 of the lower bolts on the intake manifold. These bolts are in place, but not tightened down as they should be. All the other bolts are.
Don't hear any air hissing, but is it still possible that those 2 bolts are the cause of these problems?

I'm really at a loss here...

mpgmike

One issue that might be relevant is when swapping engines where the crank sensor is mounted in the bell housing, the CS must be removed. I've seen countless engine swaps where the CS was banged getting the engine & tranny together. Don't know Hondas well enough to know if this is an issue.

Next issue is pinching wires accidentally. Maneuvering an engine around sometimes gets something smashed. Did you check your wires and connectors for damage? If you have the ability, check for pending codes. These are not hard codes yet, but the ECU is suspecting something. I've found many issues this way.

Hope this helps,
Mike

BlackFox

Crank sensor is on the front of the engine if I recall correctly, we haven't been banging it around to much either.

Wires and connector all seem fine, unless there's something broken beneath all the protective covering.

I don't get a CEL light and it doesn't give any codes via OBDII.

GagnarTheUnruly

iTrader: (3)

It would be a good idea to check compression, valve timing, ignition timing, and valve clearance.

What is the engine and what is the chassis? Both S2000?

BlackFox

Both are AP1 S2000 indeed

GagnarTheUnruly

iTrader: (3)

This sounds exactly like the problem I had when my valves were set too tight by a previous owner. That's where I'd start, but other things could cause the same problem.

Enjoy your AP1! I hope to have one myself some day.

BlackFox

Considering the fact it has titanium valve retainers, that is a possability.

You'd also have the same cold engine and warm engine symptoms as me?

GagnarTheUnruly

iTrader: (3)

My symptoms were:

Initial cold startup: fine, and idled strong but low, and with a bit of a "popping" noise
Any throttle input: car would die, or come very close to dying and would resume a very low, rough idle with a pronounced pop. I believe I was getting some misfires but not enough to trip a CEL.
Car died: would require throttle input and lots of turning to start

I could drive around town but the car would die sometimes when I held the clutch for a long time during gear changes and when I came to a stop. The engine also sounded "off," like it was running rich or retarded and it had a slighly dull throttle response. My valves were at almost zero lash. When I corrected them the problem went away and the engine sound improved. Someone less experienced with Hondas would not have noticed a difference in sound and throttle response -- it was subtle.

My problem was worse in the cold, but I'm not sure that means much. Your argument about the high cold idle easing the problem makes sense. When I swapped in an ECU with a little more startup fuel and higher idle rpm the problem was much better.

BlackFox

Does sound logical and resembles my problems indeed.
My cold startup however is high, it's at around 2000rpm, with indeed a popping noise from the exhaust. (mind you, do have a testpipe and exhaust bypass pipe to make it a bit more sporty... and loud)

Car doesn't die from the throttle input itself, it dies from releasing the throttle.
Also quite strange: If I try to keep the revs at say 2500rpm, the revs will start to drop without me moving my foot.

mpgmike

When replacing valvetrain components, different metals expand & contract at different rates. You might want to back off on the lash a bit and see if that helps. The old Hondas were to be adjusted cold. Most other makes adjust valves hot. Maybe try adjusting them hot to make sure you have sufficient clearance.

Mike

BlackFox

Vavles were indeed a bit tight, adjusted them. Also bolted down the 2 intake manifold bolts that were loose, replaced a damaged vacuum line.

Still no change.

Car idles normally when cold, but exhaust pops quite a lot? As soon as the coolant reaches temperature, the troubles really start.
When driving it feels down on power and hesitates at low rpm. Above 3000rpm it just doesn't feel as fast as it should be. VTEC does work (only briefly touched 7000rpm for testing), but isn't as aggressive as it was.

Maybe timing is off?

mpgmike

When all else fails, go back to basics. Try performing a compression test both cold and hot. If that checks out, add a vacuum gauge to see what you have. If you have low vacuum, check exhaust system for clogs (or lost rags from the install). If the vacuum is bouncing, look for a single cylinder that is messing up the vacuum signal to the MAP. It almost sounds like it works fine in open loop, but then gives you trouble when it switches to closed loop. Look for other commonalities that could shed some light.

Did you buy the engine from someone you trust? Maybe there's a reason he went with the Toda besides upgrading. How did the car run before the swap? etc, etc.

Mike

GagnarTheUnruly

iTrader: (3)

Sounds like it's misfiring to me. Get the engine warm and then check spark. That's another thing to try.

Usually problems that get worse as the engine warms are ignition problems, I believe.

BlackFox

We also did a compression test, but I think the results were off because we couldn't get the rubber seal all the way down the spark plug tube, so we just measured it on top of the tube. And we did get an equal result for all 4 cylinders, but they were all pretty low. Probably because we didn't actually got to measure at the spark plug hole itself?
Adding oil didn't raise the compression.

I do not have acces to a vacuum gauge I'm afraid...
The engine works "fine" above 3000rpm and at full throttle if that is what you mean by open loop? It just seems to hold back on the power.
No throttle = problems. For a temporary solution we adjusted the screw on the throttle body so it will stay at approx. 800rpm without stalling. At least it's more driveable now.
I know this is not a proper solution and definitly not permanent!!
This also has a weird side effect sometimes. When "idling" at a red light (not really idling ofcourse since the throttle is a bit open), the revs will sometimes bounce between 1200-2000rpm. And then slowly dropping to 1000-1600 and then idle perfectly normal at 800-900. But it won't do this all the time.

The engine came from someone I should trust, yes. I also talked to him today on the phone and he also said the engine ran absolutly fine before selling it. It felt like a totally standard engine to him and according to him there were no parts replaced by tuning parts (except for the valve retainers apparently). He did ran it with ITB's and an AEM ECU though.
Someone else on a Belgian/Dutch S2000 board also saw and heard this engine perform and agreed that it was flawless. The mechanic who adjusted my valves said the same thing, he doesn't suspect the engine to be faulty. In his opinion the engine sounds fine and responds very well.
I however know as a fact that my previous engine idled beautifully and pulled much smoother and stronger then this one.


Although I have a testpipe fitted, the exhaust does smell pretty strong like petrol.


Maybe it's also possible that my petrol has gone bad in the 3-4 months it's been sitting outside in the cold and rain?
The tank is almost empty now, so I'm going to fill it up with fresh petrol and see if that might make a difference.

BlackFox

Misfire at low rpm only? It doesn't hesitate at higher rpm, it just feel like it isn't performing like it should. As if it doesn't get enough air.

If I am correct, a misfire should also throw a CEL?

I think a misfire is a more noticeable aggressive feeling, the hesitation I notice and feel makes me think it's got something to do with air/fuel mixture problems. But I'm not a mechanic, so I might be wrong ofcourse. Just trying to think logically.

BlackFox

Just drove it around a bit more and it might be my imagination.. but it seems to drive pretty normal.
Low revs still don't feel like it should, but it's not a big difference. Higher revs also feel quite normal, and it does pull rather nice now without hesitation.

Idle is probably still a problem though, don't think it will solve itself.

BlackFox

Disconnect the knock sensor today to rule that out as well. Didn't make a change... didn't gave a CEL either??

Got some movies as well.

Idle, with idlescrew turned up a bit:


This is where I try to keep the revs constant without moving my foot. You can see the revs slowly dropping and then rising a bit without me actually moving the throttle. The big dips is me ofcourse.



This is with the idlescrew of the throttlebody turned down again. This is the original problem.

BlackFox

Anyone?

Car also backfires when releasing throttle at 5000rpm in neutral. (not loud, but the exhaust pops, didn't use to do that)

BlackFox

Reinstalled the cat to see if it would pop a CEL... nothing.

At WOT everything is alright, pulls very strong without hesitation.
Every other throttle position and it will hesitate and jerk about. Also slightly shaky when idling (at 900rpm approx.).

I can also make an OBDII log of all the ECU and sensor values with Dashcommand, anyone that knows how to read these values?

GagnarTheUnruly

iTrader: (3)

Post them if you've got them -- it can't hurt. Have you voltage-tested the sensors? MAP, TPS, ECT being the most important probably.

BlackFox

Not yet since I don't know the right proceedings? Is it possible to just stick the needles of a voltmeter in the connectors, or do I have to strip the cables or something?

I will try to swap the MAP sensor and the IACV with those from another S2000, hopefully this weekend.

Which one is the ECT?

GagnarTheUnruly

iTrader: (3)

Engine coolant temperature. Not sure if you guys even have one.

You'll need to get your hands on a shop manual for the electrical troubleshooting. Usually it's just connecting a multimeter to one or the other end of a connector and checking voltage under different conditions (i.e. throttle fully open and fully closed). You then check the appropriate connectors on the ECU to make sure the ECU is getting the signal the sensor is sending.

Shop manuals have very useful flowcharts that might help you as well.

BlackFox

We do, it's in the back of the intake! When we first started the engine we got a CEL and no coolant temp in dash because we forgot to connect that one!

I have a service manual and it does state the trouble shooting methods! Haven't thought about that one :D

Here is a log I made with dashcommand, in neutral at idle and at about 3000rpms for testing:

http://www.sendspace.com/file/gppmie

You'll need ScanXL to read it I think.

The service manual states the TPS should be at around 6% when throttle fully closed and around 90% when throttle fully open... it is around those values. So I can probably rule out the TPS.
The MAP sensor should be around 101 kPa with ignition off... that is also correct...

BlackFox

Finally it popped a CEL!!!*

Changed the oil today (previous owner had 0w60 for track use... Now 5w30)

During testdrive the CEL came on with codes p0170 and p0172, system too rich.

GagnarTheUnruly

iTrader: (3)

Doesn't help much because the CEL is more a symptom than a cause. You've got some sort of tuning problem. Either the mechanical systems aren't functioning correctly (e.g. vacuum leak, fuel clog), the sensors are sending the wrong signals (sensor problems), or the ECU is recieving the wrong signals (wiring problems or faulty ECU). You're going to need to use a carefully planned troubleshooting procedure to isolate the problem. That's where the Helms manual comes in.