S1 with 2.9 hesitation
Discussion
Well, I finally got a chance to take my new S1 with the 2.9 out on the road this morning. Overall it had fantastic power and felt quicker than the 2.8, but it has an annoying hesitation when just going off idle to get going again. It seems like fuel starvation, but in general it smells very rich and pops at idle, so I'm wondering if the fuel regulator might not be working correctly at idle, and the engine is getting too much fuel when I open the throttle, then evening out as more air is available?
When I got the car it wouldn't start due to fouled plugs, caused by rich running. I replaced the faulty coolant temp sensor and now it seems to be happier and starts easily.
Has anyone experienced anything similar?
Cheers,
David
When I got the car it wouldn't start due to fouled plugs, caused by rich running. I replaced the faulty coolant temp sensor and now it seems to be happier and starts easily.
Has anyone experienced anything similar?
Cheers,
David
Thanks Damian. I did take the AFMs off and look at them, but I wasn't exactly sure what to look for, other than cleanliness and smooth operation, which were OK. I haven't cleaned the ISCV yet, but I did unplug it to make sure it was doing something and that the minimum air screw hadn't been messed with. Unplugged, the engine stumbled a lot but kept running, which I think is correct. It does hold a good idle cold and warm with no fluttering so it seems to be OK, but I will give it a clean tomorrow.
One reason I suspect the FPR is because it makes a noise when the engine hesitates. It's a quiet clicking noise, and might be normal but I can't think of a good reason why a regulator would make any noise at all unless the diaphragm has become stiff.
I was hoping that it would be something to do with the ECU and by driving it a bit it would re-learn how to run smoothly. I only drove about 10 miles today in a variety of situations, but it didn't clear up at all.
One reason I suspect the FPR is because it makes a noise when the engine hesitates. It's a quiet clicking noise, and might be normal but I can't think of a good reason why a regulator would make any noise at all unless the diaphragm has become stiff.
I was hoping that it would be something to do with the ECU and by driving it a bit it would re-learn how to run smoothly. I only drove about 10 miles today in a variety of situations, but it didn't clear up at all.
An update on my hesitation issue.....
I replaced the FPR today, but it made no difference at all. I unplugged the TPS and it revved smoothly, so just to make sure it wasn't just because the ECU had gone into limp mode, I disconnected one of the MAFs, reconnected the TPS and the hesitation returned. Next, I removed the TPS but left it plugged in and it revved smoothly. I don't have an analogue meter so I can't really test the TPS fully, although the min and max voltages are correct. I sprayed a ton of WD40 into it and will leave it overnight to see if it helps.
I replaced the FPR today, but it made no difference at all. I unplugged the TPS and it revved smoothly, so just to make sure it wasn't just because the ECU had gone into limp mode, I disconnected one of the MAFs, reconnected the TPS and the hesitation returned. Next, I removed the TPS but left it plugged in and it revved smoothly. I don't have an analogue meter so I can't really test the TPS fully, although the min and max voltages are correct. I sprayed a ton of WD40 into it and will leave it overnight to see if it helps.
AutoAndy said:
Interested to know how you get on David, as I may have the similar problem....
Since I don't know what all those letters stand for I am forced just to drive fast to avoid low speed running...if only there was another way...
Since I don't know what all those letters stand for I am forced just to drive fast to avoid low speed running...if only there was another way...
Not sure if serious...
but just in case:FPR = Fuel pressure regulator.
TPS = Throttle position sensor ( throttle pot )
ISCV = Idle speed control valve
AFM = Air flow meter ( same thing as MAF below )
MAF = Mass air flow ( meter/ sensor )
WD40 = Utterly magical wonder spray stuff.
HTH
HTH = Hope this helps
Edited by glenrobbo on Saturday 18th January 09:42
Well, it seems to have improved a bit. Either that or my technique is improving and I'm making up for the hesitation. It goes like the clappers once it's past the flat spot, so the TPS is mostly OK. Next step will be buying a cheapo analog meter to see if I can see what's going on before buying another part that I don't need.
glenrobbo said:
Just a thought David, does your throttle lever have a J- slot or the modified straight slot to improve throt tle response?
Glen,I think you're on the right track. There are two butterflies on this engine and I would think they should be synchronized, but they are off by quite a bit. The hesitation is in the range where the first throttle opens, but the cam slot hasn't started to open the second throttle, which has the TPS attached to it. I have been messing with the roller position and it seems to be making some difference, but the slot profile is quite flat to begin with so I can't get both butterflies to synch properly. If I move the butterfly shaft with the TPS on it, everything is good, so I think the TPS is fine after all. I need to figure out what's not right and adjust accordingly, but I can't find any guidelines on the web......
Is the slot modification a 2.8 thing, or 2.9? I'm going to go and see if it has signs of being tweaked.
ETA: I'm full of it. Both butterflies are on the same shaft, so they will be synchronized of course! I found that the revving was normal when I took out the crank breather hose, so it's gagging for air. The breather hose is actually heater hose and is completely collapsed, so I'm going to get some stouter hose and see what happens....
Edited by Loach1 on Saturday 18th January 18:50
It's a 2.9 mod. I remember seeing it on here a while ago.
It may have been Rob ( GriffinR ) or Mike ( Phillpot ) ???
Makes it smoother lower down the rev range I believe.
Edit: David, search on here for " serious rookie error" a 2011 thread, page 2 should be helpful.
It may have been Rob ( GriffinR ) or Mike ( Phillpot ) ???
Makes it smoother lower down the rev range I believe.
Edit: David, search on here for " serious rookie error" a 2011 thread, page 2 should be helpful.
Edited by glenrobbo on Saturday 18th January 19:05
Thanks for that Glen. It looks easy enough to do, I'll add it to the list.
Good news - I replaced the breather hose and it fixed the problem! The shop didn't have vacuum hose so I still have a heater hose for now, which will probably collapse very soon because the vacuum is pretty high (low?). That was a bit of a head-scratcher, but a nice cheap solution is always welcome. Time to go and see if the shop on the other side of town has 1/2" vacuum hose.......
Good news - I replaced the breather hose and it fixed the problem! The shop didn't have vacuum hose so I still have a heater hose for now, which will probably collapse very soon because the vacuum is pretty high (low?). That was a bit of a head-scratcher, but a nice cheap solution is always welcome. Time to go and see if the shop on the other side of town has 1/2" vacuum hose.......
Loach1 said:
Thanks for that Glen. It looks easy enough to do, I'll add it to the list.
Good news - I replaced the breather hose and it fixed the problem! The shop didn't have vacuum hose so I still have a heater hose for now, which will probably collapse very soon because the vacuum is pretty high (low?). That was a bit of a head-scratcher, but a nice cheap solution is always welcome. Time to go and see if the shop on the other side of town has 1/2" vacuum hose.......
Good news - I replaced the breather hose and it fixed the problem! The shop didn't have vacuum hose so I still have a heater hose for now, which will probably collapse very soon because the vacuum is pretty high (low?). That was a bit of a head-scratcher, but a nice cheap solution is always welcome. Time to go and see if the shop on the other side of town has 1/2" vacuum hose.......
I believe there's a custom shop near Long Beach CA that has some in stock
Or you could stick a coil spring down the bore of the hose......
Edited by glenrobbo on Saturday 18th January 20:06
glenrobbo said:
It's a 2.9 mod. I remember seeing it on here a while ago.
Makes it smoother lower down the rev range I believe.
Really has nothing to do with how the engine runs, it is purely a modification to the throttle linkage, but does make the throttle response "snappier"Makes it smoother lower down the rev range I believe.
This is a standard one.....
There were a few from the factory that are straight, or that type can be modified, not the clearest picture....
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