Problems While Driving At Cold Engine

[martin81 1]

Hi.. I've tried to search the forum but no answers..

 

Im lacking power while accelerating(normal) when the engine is cold..

Ive noticed that idle is normal, it rund at about 1500 from cold, but drop after some minutes to 500 rpm..

 

When im driving it kind of deccelerates when I accelerate.. Lacking power..

 

If I go full throttle them it acc normal..

 

As soon as the engine is warm, then everything is normal..

 

The problem accured recently..

 

Any ideas???

[DrSarty 90 1 Cars]

There are answers - lots of them.

 

You should look at topics concerning the SAD (supplementary air device), where you could check the connections to it, and perhaps also clean out the breather hoses and check them and your inlet air system for cracked and split hoses.

[martin81 1]

Ive cleaned the SAD many times... I do think there might be some cracked hoses somewhere, as I can block the AFM, and the engine still runs roughly.. BUT thats been there for some time now.. This just happened recently.. Ive read almost every post about SAD and idling, but didnt find anything like my problem...

 

I know there are three temp-sensors, one that signals the ECU, one that signals to the dash, but what about the third??

 

Im thinking lambdaprobe, ECU-temp-sensor, or perhaps TPS..

Because while driving normal, the car lacks power, almost deccelerates.. Unless I go pedal to floor.. Then it accelerates as it should...

When warm.. it accelerates normal no matter how...

 

The problem is only when the engine is cold

[DamirGTI 342]

If you have an air leak (as you say by this the AFM blocking test) do fix it asap ..

 

As for the rest , id give it a few deg. of ignition advance and see how it goes then

 

Damir

[DrSarty 90 1 Cars]

The air leaks are critical to fix as Damir says.

 

You never mentioned the car year or type, but now you've mentioned a lambda. What engine is it exactly?

 

As for the 3 thermostat housing water temp connections: 1 is for the ECU (a sensor), the other 2 are a sender and a switch for the temp gauge and water temp warning light on the dash.

 

I am not an expert on the Jetronic to Motronic changeover, so I'm not sure if you have a TPS (switch) or TPS (sensor). If it's the switch type, then you can disconnect it and see how the car runs. I wouldn't advise wide open throttle (WOT) as that's when the switch clicks and enriches the fuel. But up to that point - and if you've fixed your air leaks first - if the engine runs fine then the problem wasn't the TPS.

 

Hope that makes sense.

[martin81 1]

Ok Ill try to fix the airleak asap.. Why is it critical?? Because of the low fuel/Air ratio??

Its a 1,9 cti with lambda... From 1990.. Its the 102 bhp.. Cant remember if its dfz or dkz... Low CR , but Ive put on a xu10 with std camshaft.. But as mentioned it started recently... Ive fidled with the ignition.. Retarded it because of the higher cr..

[DamirGTI 342]

Yes , EFI cars , particularly multipoint ones are very sensitive on air and vacuum leaks .. leaks on the areas from the AFM inlet above wont make any difference but the ones from the AFM outlet down the inlet tract till the manifold/cylinder head will certainly do as this false air wont be measured within the AFM and thus not calculated in the air/fuel ratio via AFM/ECU .. the mixture will go lean and if the car is CAT equipped it might set the mixture faulty code as well because of the higher exhaust oxygen content (as well as in the case of misfiring ..) ... symptoms of vacuum/air leaks will have effect on the idle speed , part throttle , full throttle causing jerky idle speed , hesitation etc. etc.

 

 

Its the 102 bhp.. Cant remember if its dfz or dkz... Low CR , but Ive put on a xu10 with std camshaft.. But as mentioned it started recently... Ive fidled with the ignition.. Retarded it because of the higher cr..

 

But this'll be your main problem it wont do like that , if the CR is raised (though , you haven't said by how much ?) you'll need to re-set the dizzy advance curve to make it work properly , by retarding the timing in order to stop the pinking low down you'll loose both power/torque and economy .. all coped with crappy engine response and erratic behaviour at idle ..

 

Damir

[martin81 1]

Reset it??? How??

[DamirGTI 342]

By writing down on a piece of paper all the engine mods/specs , wrapping up the dizzy and sending it to this boys :

http://www.h-h-ignitionsolutions.co.uk/

... recurving job is around 20,00 quid + postage , and yes it's not something you can do on a DIY basis by yourself

 

Out of curiosity , how high is the CR ?! you've fitted XU10 head on a XU9 DFZ block ?

 

Damir

[martin81 1]

Yes.. But dont know the exact CR.. I cant remember the cc of the

xu10 head. All I know is that the head has gone through a minimal skimming. So the cc should be standard. Combined with standard block and pistons of a 1,9 cti and headgasket..

[martin81 1]

Just tried to fiddle with the ignition again.. Still same lack of power with cold engine.. As soon as the temp reaches 70 degrees then it acts normal... Could it be tempsensor? Lambda? Or SAD??

 

As told before, when I start it from cold, it begins with 1500 rpm.. But after a minute or two, it hits 500 and sounds like running on two or three cyl. If i rev it up, then it sounds ok and pulls ok.. Its like when its running idle or just over.. At about 2000-2500 rpms.

 

And as told, it ran well before.. It just occured one morning.. Without fiddling!

[martin81 1]

now ive expirienced when warm also... ill try to swap the fuel filter, plugs, dizzy cap and arm... maybe then see what happens.. i cant find any airleaks from AFM to manifold...

[DamirGTI 342]

Well it'll be high CR somewhere @ 11 mark .. cos XU10 head has shallower chambers than the XU9 DFZ head , even shallower than the XU9 D6B head ! + it has bigger inlet valves , different port shape , different inlet manifold , different cam profile ... so when bolted on a XU9 DFZ block (which has 1.6 type pistons with low 9cc dish and tall compression height ..) the end result will be - loads of CR ... so id honestly suggest that you reconsider tuning up this engine properly until something goes wrong - it'll need different ignition timing specs and more fuel !! std. just wont do , i've experienced something similar before on my engine ..

 

Yes it could be some engine management sensor broken , could be sticky injector etc. and you might even have a head gasket sealing problem (Xu10 head + Xu9 block is a bit of a hit and miss with regards to the head gasket choice..) and so on , but that might be because of the wrong engine set-up too (wrong ignition timing can damage the head gasket like you wouldn't believe .. it's the first and most common reason for head gasket failure - detonation ..) this'll need to be sorted asap if you wont this engine to perform at it's best , performance and reliability wise ..

 

Now , i would like to know on which engine management are you running this engine ?

 

Damir

[martin81 1]

Well it'll be high CR somewhere @ 11 mark .. cos XU10 head has shallower chambers than the XU9 DFZ head , even shallower than the XU9 D6B head ! + it has bigger inlet valves , different port shape , different inlet manifold , different cam profile ... so when bolted on a XU9 DFZ block (which has 1.6 type pistons with low 9cc dish and tall compression height ..) the end result will be - loads of CR ... so id honestly suggest that you reconsider tuning up this engine properly until something goes wrong - it'll need different ignition timing specs and more fuel !! std. just wont do , i've experienced something similar before on my engine ..

 

Yes it could be some engine management sensor broken , could be sticky injector etc. and you might even have a head gasket sealing problem (Xu10 head + Xu9 block is a bit of a hit and miss with regards to the head gasket choice..) and so on , but that might be because of the wrong engine set-up too (wrong ignition timing can damage the head gasket like you wouldn't believe .. it's the first and most common reason for head gasket failure - detonation ..) this'll need to be sorted asap if you wont this engine to perform at it's best , performance and reliability wise ..

 

Now , i would like to know on which engine management are you running this engine ?

 

Damir

 

im running std lu2 manegement..

It doesnt use water and oil, or at least a minimum of Oil..

Now im really considering swapping engine again.. Hate it.. Ill try to fiddle with it tomorrow at work.. If I make it so far...

Thank for your answers...

[kennygti 0]

also having similar problems with my standard 1.9 8v. Although mine has been stood for 4 years so probably doesn't help much. Hoping to take a look at mine in more detail tomorrow.

if you manage to solve your problem martin any pointers would be appreciated at my end.

 

Kenny

[martin81 1]

Think ive solved it.. The breatherhose underneath the inlet manifold is cracked.. So it has been pulling false air through it.. And when the SAD closes the amount of air is reduced, which makes sense why it acts almost normal when warm..

 

The var accelerates beautifully when warm after I changed the ignition almost back to normal.. Only thing now is if I go full throttle from liere revs, then it knocks for Hald a second or so...

[DrSarty 90 1 Cars]

check them and your inlet air system for cracked and split hoses.

 

I don't want to say it...but I told you so.

 

Glad you got it sorted. From the symptons, it certainly sounded like badly metered air, entering via the SAD or some other means.

 

Awesome.

 

The knocking is probably because you have an odd combination and you've "fiddled" with the timing.

[martin81 1]

Hate the spelling on my iPhone.. Hope you'll can understand it Well I haven't tried it out yet but I think that had to be the problem.. The air leaked a lot when I used high pressure from the other end.. Ive changed the water temp sensor just as well, now the engine was torn half apart..

 

I appriciate all your responces..

 

And for all who experiences problems with idle and so.. Double check all breatherhoses!! Inclusive the bolts on the right side of the inlet manifold..

 

Ill let you know how it goes when its reassembled...

 

Have a great weekend

[martin81 1]

well... it still act weird... ill try to "reset" the ecu, by disconnecting the battery overnight...

 

maybe some other part is faulty... hmmm

 

maybe it will get better, when it take it for a spin tomorrow morning

[martin81 1]

Well, it didnt help much.. When cold it runs ok at idle, but it still stalls when driving... As soon as it hits 70 degrees or above, it drives very nice.. But idles like crap... It revs up and down continously, down to 500 revs and up to 1500, down to 500, and so on...

Could it be TPS, Cold Valve or lambda probe???

Now I think ive solved the false Air problem

[martin81 1]

A new lambda probe helped a lot!! Now Im waiting for new TPS and SAD to arrive and installed...