Shocking performance when hot!

JonRobinson82

Hi guys (and gals maybe)

I'm getting seriously shocking performance when the car is hot now we have some scorching weather! I mean I know an engine loves cool and damp but why such a difference when the engine has got hot?! I'm talking about after running for a while. Was at Southend the other night and acceleration was so poor I was embarrassed! I've replaced all my vacuum pipe as it was in about 5 pieces all duct taped together but no matter what Torque is reporting for intake temperature (today 45 but the other night down Southend it got up to 60s) it seems crap.

It's a 2.2 Vectra B CDX with K&N panel filter, completely derestricted airbox, triple plugs and a genuine latest model GM coil pack. It also has a Klarius "type approved" cat, straight through middle pipe on the exhaust and the rear box from a CDX diesel as it was better condition than mine.

Whether it is related or not I also get a strange cut in power every now and then, moreso on hot days. It used to backfire a little before I got the cat replaced and the exhaust sealed up properly but now it just dies like you've took your foot off the pedal then planted it again and it seems perkier after that for a while.

HEEEELP!!! I'm lost lol

JonRobinson82

Oh also it's had a new fuel filter

Berto

Some points I'd check in your case:

· Re-check the vacuum lines.

· IAT (Intake Air Temperature) sensor on airbox to TB pipe.

· CTS (Coolant Temperature) sensor on thermostat housing.

· O2 sensor.

· Fuel pump.

· Coil pack.

IDI_AMIN

When is the last time you cleaned the panel filter ?

I would think that or maybe the timing chains could possibly be to blame, depends on mileage of car and when they were last done

Ivan

I have the same problem,and backfires.
Try to put pedal on the floor when you are idle.Is the rpm's dropping for second ?

JonRobinson82

Revs don't drop but hesitate.
Cleaned the panel filter the other day.
90k miles (new engine fitted at 33k cause old one ceased) and not a single noise from the engine apart from injectors tappy.
Vacuum lines seem fine.
IAT sensor seems OK.
Got a Courtenay cooler running thermostat coming so would that come with temp sensor?
02 sensors new with new cat.
Fuel pump sounds healthy and no issues when under heavy load only when hot. Cold it goes like a bullet.
Coil pack is known good second hand latest model not had the slightest issue with it so assume that's as good as it gets? Lol.

Help guys lol

Berto

JonRobinson82 said:
... no issues when under heavy load only when hot. Cold it goes like a bullet ...

^ Sounds like fuel pump and ignition are OK.

If 02 sensors are new and there are no vacuum leaks, it may be faulty CTS screwing the AFR when engine is hot. Does the engine start OK when hot, or are you having trouble starting the engine once it has been warmed up?

JonRobinson82

It doesn't start quickly regardless. Turns over for maybe 3 seconds before it starts. Can't say I've noticed it's harder when it's hot. It has trouble starting if I cut it just before it starts and sometimes backfires when you cut it.

Berto

JonRobinson82 said:
... Can't say I've noticed it's harder (to start) when it's hot ...

^ CTS is probably OK then.

JonRobinson82 said:
It doesn't start quickly regardless. Turns over for maybe 3 seconds before it starts ... ... It has trouble starting if I cut it just before it starts and sometimes backfires when you cut it.

There is a chance this is some injector-related gremlin. Sometimes when injectors are faulty they work OK when cold, but not when hot. If possible I'd do a quick & simple injector resistance test:

https://www.youtube.com/watch?v=ZVXchvHefNc

Do it first on cold engine, then on hot engine. If any injector's resistance reading is noticeably different from the others it may be faulty.

It could also be a faulty ECU that when warm fails to send correct pulsing signals to injectors. Or perhaps faulty wiring from ECU to injectors.

JonRobinson82

OK so I've got my cool running thermostat and "Water Wetter" from Courtenay, and I've just ordered a new CTS and some fuel injector cleaner from Euros. Hopefully in some way or other that all sorts it out. Fingers crossed guys.

If not I'll do the resistance check and hope I don't have to buy new injectors too much lol

Thanks guys

JonRobinson82

OK so whipped off the CTS plug and it runs better. Tried plugging it back in an bent the pins so left it off lol. Plan for tomorrow (first day off since looking) is fitting new CTS and cooler running thermostat, putting the water wetter in and also got some injector cleaner to see if it helps 🙂 but looking very promising already. Also got it booked in with Pipecraft for a quad (maybe) exhaust for it. Already got what appears to be a sports cat and the race tube in the middle so all in all should be a good couple of days 🙂

JonRobinson82

OK so cool running thermostat and water wetter from Courtenay done, new CTS fitted and completely refreshed the coolant with approx 15% coolant to water/water wetter mix. Had a bit of a mare getting rid of a poxy air lock that I got somehow. Maybe filled it too quickly but seems to be all sorted now. Boiling hot air coming out the heaters and a nice resting temperature of around 90° unless I drive, umm, "enthusiastically" shall we say lol, then it goes up to about 100° but fans all cutting in nicely and runs like a dream.

New exhaust fitting booked in for 10am tomorrow which I CANNOT wait for!! 🙂

Gonna be a happy chappy 🙂

JonRobinson82

Still got major problems when hot. You put your foot down and it's like the engine is choking. Like someone has just put their hand over the intake or sumat 🙁 I've got a K&N panel filter and done the full derestrict on the air box etc. It picks up eventually but just seems to suffer in the heat and mostly when giving it some welly it gets really bogged down til about 4/5k rpm maybe.

It's annoying me now how terrible it is when it's hot. Around 30/35° AIT seems to be the turning point.

Not sure if it makes a difference but I've now got a twin exit 3x5 ovals on the back from Pipecraft. They welded straight to my race tube in the middle so the boxes are balanced nicely. Anyways the performance is better since the exhaust got done but I've noticed it is ridiculously loud when it's hot at the same time as being crappy on performance. Finished work 6am Saturday morning and the car ran like a dream and wasn't too noisy either. That was around 20-25° AIT