opel corsa flat spot on pull away

[BTTB]

Fuel Intake Manifold

Interesting thread!

We have had Opel in our Yard since 1995 starting with the Car Of The Year the 140.
Since then we have had an Astra, Corsa and 2 Tigras.

The Corsa 1.8, Tigra 1.4 and 1,8 have all given me the same issue. Completely "pap" when you put your foot down.
On so many occasions and our cars are serviced regularly I have complained to the Service Department about this problem, so much so that when I bought my wife the her new Tigra 1.8 after we sold the 1.4 model, I insisted that the dealership sort out the software for performance otherwise I would not buy it, as what is the point of buying a seemingly sporty car if you cannot put your foot down when needed.

The other model that gave me the same issue and I still have the car as my daughter is using it is an 2002 Corsa 1.8 Executive. It was a nightmare to drive at first. Put your foot down and the car would not respond like it should. Almost as if there was a problem with the timing as in older model cars.
I managed to sort out the problem after tackling the Service Manager on the issue. They took the car in and he claims they changed the whole Computer Unit as apparently it was the wrong one for the car?? The car goes like a bomb now although the fuel consumption is not very good on that model.

Opel Corsa Bakkie 1.8
My old man has a Corsa 1,8 Bakkie which he bought from new two years ago.
When he got the Bakkie it would give about 14/15km to a litre of petrol. Then all of a sudden the fuel economy went awry and it dropped down to 7/8Km to a litre and my old man was not impressed. Took it in and claimed that they should fix it. It took the better part of 6 months to sort out that problem. In the end they swopped the Computer Unit and the Sensor Unit on his Bakkie with an identical 1.8 Corsa Bakkie they had in the yard and only then did the problem solve itself. He gets 12/13 Km to a litre now. A bit down from the time the Bakkie was new, but a lot better than 7/8Km to a litre.

Seems on the older 1.8 model motor like the Bakkie and the Corsa there is problems with the intake of fuel and my father is convinced that the little sensor unit which sits on the top of the intake manifold near the back of the engine compartment against the firewall of the bakkie is the problem.
There is no difference in the fuel consumption on the Corsa 1.8 that my daughter drives whether you drive slowly or fast. You get more or less 11Km to the litre.

Perhaps these units are the problem. Would this Op-Com be able to pick up a problem with the Intake Sensor, whatever it is called.

Other than this issue I have been reasonably happy with Opel.

 

[xsel]

Hi BTTB,
I cant say if the op-com will work with your Opels.I have not got mine yet.Expected date of arrival 25th Nov latest.
Anyways, according to the description it should work.
I can say that cartools.co.za or was it uiftools.co.za said that they had used it successfully on the corsa UTE.
It is supposed to pick up any sensor errors stored in the computer.
Also, it is supposed to give real-time graphs-it connects to your laptop(usb).Great hey!

 

[xsel]

Sunday 8AM-an update:
OK, I dived under the bonnet,to check out the exhaust finally.
And found that I need a special no 8mm socket to get the exhaust manifold heat-shield off.
Now, where to find one of those?(Builders warehouse)

Anyway, we continued the good fight,and tightened what I could,13mm on the 8 manifold
bolts holding the 4 ports to the head,but wait,I only found 6 bolts.
The 2 outer ports top and bottom bolts found,and tightened,but I only found
top bolts on the 2 inner ports.The Exhaust manifold cups the bottom holes,so only
a socket can go in there(after the heat-shield is off).I found stud stubs in there.
This has to be wrong.
This now apears to be a exhaust specialist job.
Agreed?

I think the flat spot is gone(almost), but the poor acceleration is still there.
But I must first sort out the 2 broken studs on the exhaust,before I can really say for sure
what exactly is fixed.

 

[xsel]

BTTB
I have had the cub 1988 1.3 4 speed and flew like a rocket.
Also,I had the kadett 4 speed 1.4 1995 I think it was,and that one flew as well.
Then I got the Corsa UTE 2003 1.4 and that too was a pocket rocket.
Just this Corsa 2006 1.4 UTE is a dog at low revs.......

 

[xsel]

DuCy
I look forward to hearing the outcome.
Be sure to interrogate the Service Manager on exactly what they fixed,
or else he will just brush over it.

 

[BTTB]

BTTB
I have had the cub 1988 1.3 4 speed and flew like a rocket.
Also,I had the kadett 4 speed 1.4 1995 I think it was,and that one flew as well.
Then I got the Corsa UTE 2003 1.4 and that too was a pocket rocket.
Just this Corsa 2003 1.4 UTE is a dog at low revs.......

Never had any issues with the 1.4 Kadett. It was a rocket as you say.
There were two versions. The 4 and the 5 speed box. Myself and another person I know both agreed that the Kadett with the 4 speed box was the better car as the gear ratios were perfect.

The first time I encountered the "flat spot" and the laggy performance was when I got the 2002 Corsa 1.8 Executive. It was ghastly.
They (The Service Manager and Staff) apparently changed the on-board computer and "rephased" it, which I find hard to believe as the settings were exactly the same when I got it back as when they took it in.

I would love to borrow an Op-Com for a look see.

 

[Frankie]

Would this Op-Com be able to pick up a problem with the Intake Sensor, whatever it is called.

Looking at the web site, it has the capability of displaying live data from all the sensors and actuators, so yes it can help with diagnosing these types of problems, but it's dependant on someone with skills like Gnome to interpret what's being displayed.
A little bit like a doctor interpreting sonar scans.

 

[Pitbull]

Spark pluggs
Boggy Cords
or Timing

 

[Gnome]

This flat spot is with pullaway part throttle.ie,I want to get to where I want to go faster than most everyone else but not first.
So, pullaway with energy,but not full throttle,not racing.

That could very well be exhaust O2 sensor, the sensor is turned off on full throttle to protect the engine, perhaps try pulling away Wide open throttle from the get go and see if you still have a flat spot but that isn't definitive.

I didn't get the TPS and temp sensor,because the supplier flapped his mouth without checking if he had stock.

Hmm, don't buy new ones unless you have to, if you're in Pretoria try A.S.A.P Opel Spares in Pretoria Gardens, you can get some good as new stuff from there for 1/4 of the price.

Try Goldwagen first tho, you do get actual new stuff there for even less than A.S.A.P spares.

There is no pinking.

I will tell you this though;it has been bothering me for some time,
but I don't know if it is important for this diagnosis.
Quickly going 3/4 throttle and letting go,as the revs come done, there
is a burbling bubbling kind of noise,might even be soft popping,from the engine area.
I cant work out where exactly the noise is coming from.

If there was a micro hole in the exhaust manifold or the part of the exhaust in the engine compartment,would I hear a slight exhaust sound from the engine area.?
Would this micro air hole cause the oxygen sensor to give wrong info to the ecu,resulting in weak fuel mixture,and consequently , my issue described in this thread.?
How do I test if the exhaust does have a micro hole.?

Pete

Eish, ok I see now, you're car is hard to diagnose without seeing it but I'll PM you a number of a guy who knows his sh*t, if you're not in Gauteng tho, check:

* Timing with a timing light.
* Fuel pressure with a fuel pressure tester.
* Exhaust O2 with a O2 sensor so you can confirm if the Air Fuel mix is correct.

You can *try* compression test but I doubt you'll have a problem there, performance would be down right through the range if the head gasket went or say the rings where finished, you'd also see smoke from the exhaust and so forth.

Now the timing light and fuel pressure test is quite easy, same for a compression test so anyone doing that shouldn't be charging you very much,.

The exhaust O2 is the last resort because you'll need someone who knows what they are doing or at least another perfectly working UTE to compare the values to, having another UTE is also useful since you can check and compare the values but if it's someone who knows their Opels they'll have those values on hand anyway.

Oh and just to be sure I'd check the physical timing first but probably that isn't a issue.

Btw. I don't work on the cars daily or anything, so I'm not a expert I just gave my opinion to try and help, SO please listen to what the experts say rather than what I told you BUT also use common sense!
The stuff I learned was because my Opel was giving me some problems and I picked the stuff up as I didn't have the Cash to spend and began fiddling around with help from some Opel experts.

 

[Gnome]

This now apears to be a exhaust specialist job.
Agreed?

Yep, phone a few exhaust places and get some quotes, then take it there, can't be charging too much.

 

[xsel]

Gnome
I did the exhaust job myself last night.
A really affordable Stud Remover tool was the key.
(new manifold and flange gaskets,gungum,new studs)

I took the bakkie for a test drive, and noted:
When cold I can now confirm, the flat spot is there on gear changes,but full energy
is available throughout-one sweet flow.
When warm,from 1/4 on temperature gauge, the flat spot seems to be gone,or minimal,but
that holding back is there until 2500rpm or just below.
Jerkiness on pullaway is still there(sometimes-BUT not as strong as before the exhaust job).

The burbling when revs come down is definitely on the inlet side of the engine.
There is still a slight exhaust noise, after the exhaust job,so I am now assuming that
this must be normal.
The old exhaust manifold gasket showed a bit of black soot pointing down to to
the missing bolts on the 2 inner ports,but not really much more than that.

I looked at the o2 sensor and the part that is in the manifold is WHITE/LIGHT GREY.

Sofar, it looks like this exhaust job I have done has had some success.

Finally I can say, that pulling away at full thottle exhibited the following:
Tyres slip slightly,and it seems like the bakkie wants to pull away FAST,
but then that holding back thing is there until 2500rpm.

I hope this will help narrow things down so this thing can get sorted.

Geez, I must say, a unichip is beginning to look very very good right now...... (money's run out,so not an option)

Thanx/Pete

 

[xsel]

An update:

I finally got some cash together and tried tackling this issue again.
A local garage said he would find the issue causing the flat spot on pull away.
He cleaned every sensor,and every Earth connection,and a slight improvement occured.
He replaced MAP and O2 sensor with his(1800 Ute)and it performed better.
I went and got pirate parts and replaced same,but it did not seem to be as good,or just the same.
While sorting out a wheeel alignment issue,I drove the wheel alignment's UTE,and it drove just like mine.
It is my conclusion that these vehicles tend to drive like this,through some inherent design fault,and if I don't like get , get another car.
I don't know what else to check.
Fuel pressure?
Injectors?
harness?
Computer?
drive it off a cliff?

Cheers/Pete

 

[xsel]

The final update

I fitted new spark plugs and flat spot miracously vanished,well nearly, but so little of it left that I will declare it fixed,especially since the cash ran out again.
BPR6ES by mistake instead of BPR5EY,but it goes well now anyway.
Only porcelain is slightly shorter by the gap,which is 1mm.

I hope my saga has helped you.

Cheerrs/Pete

THE END

 

[Gnome]

Then you can count yourself lucky, the BPR5EY is a hotter plug than BPR6ES, the reason the car had "flat spots" or lag is because the hotter plug was causing pre-ignition, only the ECU detected the onset of knocking and decreased the spark advance to prevent damage which you felt as lag or flat spots. Better low performance than a piston with a hole burnt in it I would think...

NGK has extensive info on why it happens if you're interested.

Btw. it's a common occurance, non-GM service stations and over the counter spares stores commonly sell the wrong plug or "similar" plugs. It's happened to me at Midas especially, I ask for NGK BPR6ES and then the guy gives me NGK BP6ES (they don't have BPR6ES) and when I ask him WTF, he tells me they are the same?!

 

[Frankie]

A friend emailed this to me, and I thought some here would also find it interesting.

What is a racing plug?

Most "racing" spark plugs are just colder heat ranges of the same street versions spark plug. Their internal construction is no different than their standard heat range equivalents. Racing spark plugs do not make more power in an engine, rather, they allow the engine to make more power. Meaning, after all the engine modifications are done that add power, a racing plug is better designed to operate in the torturous conditions created by those modifications. If you used a regular plug in a modified race engine, it would quickly be destroyed, while a properly selected racing plug would endure the extreme limits of that motor. Take that same racing plug, however, put it in an unmodified motor, and it would foul out within minutes.

The differences between a racing plug and traditional plug are not solely heat range. There are firing tip configurations necessary for survival in alternate fuel racing and situations of extreme boost/compression (such as retracted-nose insulators or surface gap firing tips), which would run very poorly in an unmodified motor. However, there are some very effective race plug design features including ultra-fine wire electrodes,gold palladium, platinum, iridium electrodes and cut back ground electrodes that are now available in standard non-racing heat ranges, these can maximize fuel combustion and improve performance in unmodified motors as well.

When are racing plugs necessary?

Not all modifications would require the use of racing plugs. Modifications that do not alter the overall compression tario will not usually necessitate changing plug types or heat ranges. These would include free-flowing air filter, headers, mufflers and rear-end gears. Such minor modifications will not significantly increase the amount of heat in the combustion chamber, hence, a plug change is not warranted. However, modifications that introduce new fuel types or alter compression ratios such as turbo charging, supercharging, nitrous oxide injection, modified cylinder heads or piston configurations, to name a few, generally require a change from stock spark plugs. This is because, with compression increase comes additional heat which requires a colder plug, with fuel and altered piston/plug clearances can come firing tip configuration changes. Typically, for every 75-100 hp you add, you should go one full step colder on the spark plug's heat range (eg. NGK BP7ES to BP8ES or Iridium equivalent). If you have gone too cold you may see severe oil or fuel fouling

Heat range

The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.

The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.

An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.

The heat range numbers used by spark plug manufacturers are not universal, by that we mean, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite. Some manufacturers numbering systems are opposite the other, for domestic manufacturers (Champion, Autolite, Splitfire), the higher the number, the hotter the plug. For Japanese manufacturers (NGK, Denso), the higher the number, the colder the plug.

Iridium

Iridium is a precious metal that is 6 times harder and 8 times stronger than platinum, it has a 1,200(=F) higher melting point than platinum and conducts electricity better. This makes it possible to create the finest wire center electrode ever. Prior till now, platinum had been favored for long life or performance spark plugs due to its high melting point, also the technology did not exist to machine and bond iridium on a spark plug electrode(at least in a cost effective manner). Iridium industrial spark plugs have been around for years, but still sells for over a hundred dollars per plug. Just now is the technology available to effectively use iridium in a spark plug for automotive applications. The strength, hardness and high melting point of iridium allows NGK to manufacture their iridium ultra-fine wire center electrode to 0.7mm. One of the finest firing points in the industry! (Thus far there has been no problems reported regarding use of iridium plugs with nitrous oxide.)

General :

Do not make spark plug changes at the same time as another engine modification such as injection, carburetion or timing changes as in the event of poor results, it can lead to misleading and inaccurate conclusions (an exception would be when the alternate plugs came as part of a single precalibrated upgrade kit). When making spark plug heat range changes, it is better to err on the side of too cold a plug. The worst thing that can happen from too cold a plug is a fouled spark plug, too hot a spark plug can cause severe engine damage

 

[xsel]

Hi

The flat spot came back!

Investigations uncovered the fact that the previous garage that did
the timing belt at 75000km did not have the proper tool for the wierd
bolt heads used on this vehicle (evidenced by all the scratches on the bolt heads)and so they did not tighten the engine mounting properly(middle of where belt is situated), and it came loose,stripping one
thread.
Thankfully that garage did the job for free,and now that mysterious flat spot is gone.

Pete

 

[Drake2007]

This is why I take the car to the dealers/agents to fix.

 

[Gnome]

Hi

The flat spot came back!

Investigations uncovered the fact that the previous garage that did
the timing belt at 75000km did not have the proper tool for the wierd
bolt heads used on this vehicle (evidenced by all the scratches on the bolt heads)and so they did not tighten the engine mounting properly(middle of where belt is situated), and it came loose,stripping one
thread.
Thankfully that garage did the job for free,and now that mysterious flat spot is gone.

Pete

Bolt heads? Where? There are only 2 types of bolts that I know of that can cause issues in regards to the cam belt.

The first is the crank pulley bolt, which if it isn't tightened correctly allows the crank pulley to move around and the engine uses the crank pulley to determine crank position for spark and fuel (it's called a 60-2 wheel for it's 60 teeth -2 of them which is the square part on the wheel, there is a magnetic sensor sitting there that picks up engine position using that wheel).

Other bolt sits on the water pump which needs to be loosened to remove the cam belt (the cam belt is tensioned by the water pump), if the cam belt moved around you are one lucky mofo that you haven't got bent valves yet.

Only those 2 influence timing and can influence performance.

If you've got the crank pulley bolt problem (it happens a lot when the cam belt is changed by n00bs) then you'll most likely run into trouble again (because they fit into each other but if not tightened properly and fitted with thread lock the key way keeping them together wears down and the crank pulley can move around on it's own), only option is to replace the crank pulley and crank gear, changing those means you need to replace the cam belt and cam belt idler also. Cam belt idler needs to be changed when you do a cam belt, according to the change interval (another item regularly skipped by n00bs), if not it can seize and the cam belt will bite down, snap, whatever, end result = bent valves.

Rather not let amateurs do the cam belt, you're asking for trouble.

 

[Drake2007]

Exactly my point,

For about a year I was having an issue with my corsa with the remedy being replacing spark plugs every so often (monthly), I did know there was something seriously wrong with the engine but hey wait for it to break properly to the point that I can not fix it myself.

Finally when my corsa wouldn't start ( i knew there was something seriously wrong with it ) it first went off to some idiot that tried to tell me it was the imobilizer keys ( some how both keys lost the imobilizer thingy at the same time).

To cut a long story short it ended up at the agents, where I wanted it to go to in the first place, with full engine rebuild and R19K later and it runs like a dream now.

btw the immobilizer was not the issue. Just some turd that trying to bull**** me.

 

[Gnome]

To cut a long story short it ended up at the agents, where I wanted it to go to in the first place, with full engine rebuild and R19K later and it runs like a dream now.

Ouch, still, there are some non-agent guys who know their stuff when it comes to Opels and you can usually get a 2L SuperBoss (125kW) engine fitted for that price excluding what you can get from selling the parts that are replaced.