Flat spot 2200-2500 revs help

D-F-A

I'm hoping that the knowledge base on the forum can solve a riddle that defeats my garage. I love my '51 150 sri, so much so that when I finally was putting as much oil into the car as fuel I decided to have another engine fitted. I found another z22se with 72,000 miles on it and promptly had it delivered to the garage for fitting. First issue was that the new lump was rigged for electrical power steering and mine was driven by the cam. So they fitted the original cam to the new engine. So far so good, however the is a flat spot at 2200-2500 revs that can be accelerated through also it occurs as you lift off briefly as for going onto roundabouts then powering back on. The fault is producing no error codes at all and is baffling the mechanic. It would seem that whilst the engine I bought is a z22se but for an astra/ zafira. Can any help to sort this problem as I love the car.....Regards Rob

Matt

Almost all these cars suffer with the flat spot you have mentioned.

Removing the pre-cat helps smooth it out.

evocarlos

egr del and ported throttle body also help but the T/B will give high cold idle speed

top tip with the z22se dont go WOT right away 🙂

D-F-A

I appreciate the advice so far lads but the previous engine accelerated smoothly through all the rev range and didn't falter at all, this engine produces this fault and whilst it doesn't make it undrivable, it is clearly wrong. Judging from your answers the engine coming from an Astra/ Zafira isn't an issue then, because I did wonder whether it was a conflict of ECUs or something of the sort. My expertise is dated i.e Mk1 AND 2 Cortinas not with computer controlled systems so please guys be gentle with me. Thanks Rob

D-F-A

Matt, sweetie, I wouldn't know a precat if it bit me....but seriously where is is the pre cat? This is a serious flat spot almost a judder not a faint hesitation. Regards Rob

D-F-A

Evo-carlos, as my post above says I'm an dangerous idiot around modern cars, ERG, T/B and WOT? It could be Klingon Jim, I'm NOT pretending I just don't understand the terminology you lads are using. Please don't stop helping though as I want my car back as it should be. Thanks Rob

evocarlos

EGR = exhausts gas recirculation valve
T/B = throttle body
WOT = wide open throttle
🙂

the egr can be blanked and the wiring dealt with using a egr cheater this will stop the black curd of the exhaust entering back into the inlet also fitting a cheater and blacking plate is cheaper then replacing a failed egr valve 🙂

the t/b can be ported (opened up) to allow better air flow thru it

next time your on a clear road try increasing the revs slowly and not foot to the floor straight away you will see it pulls up better it is a 2.2 after all 🙂

D-F-A

Blimey Evo you're answering faster than I can type. So to be clear there isn't a compatabilty issue with the lumps and ecus then? Regards Rob
:unsure:

evocarlos

D-F-A said:
Blimey Evo you're answering faster than I can type. So to be clear there isn't a compatabilty issue with the lumps and ecus then? Regards Rob
:unsure:

the only difference i know of is pre 2002 vs 2003/4 with the engine loom has different plugs (astra)
2002 has round brown thing and the other type is alot smaller and squire
all the parts when swapping the engine are the same mechanically just the wiring plugs

not sure there's a need to swap the cams for the power steering pump would have to look on mine to see if the cam has the drive fitted already

the hiccup while accelerating is a common thing with z22se i had it for a long time but i cant think of the specific thing i did to cure it as i did a few things at once then it was gone
k&n panel filter in the airbox
2 1/4" cat back stainless exhaust
egr del (at vauxhall)

ps theres no hiccup with the super charger fitted lol 🙂

D-F-A

Outstanding! :cool:

IDI_AMIN

By the way could this `Flat Spot ' be caused by oxygen sensors past their sell by date . I felt mine accelerated better after fitting a new rear oxygen sensor .But it's just i never had a name for it , which is what you are calling a flat spot. You say you have a 51 plate so that makes the car over 12 years old and also the oxygen sensors will be the same age .Guides on the net relating to oxygen sensors suggest they have a shelf life pretty much the same period as timing chains i.e. at the 100,000 mile / 10 year timescale after this amount of time they do not function the same. This could be something else to consider as i know renewing my sensors made a difference to the acceleration.

evocarlos

IDI AMIN said:
By the way could this `Flat Spot ' be caused by oxygen sensors past their sell by date . I felt mine accelerated better after fitting a new rear oxygen sensor .But it's just i never had a name for it , which is what you are calling a flat spot. You say you have a 51 plate so that makes the car over 12 years old and also the oxygen sensors will be the same age .Guides on the net relating to oxygen sensors suggest they have a shelf life pretty much the same period as timing chains i.e. at the 100,000 mile / 10 year timescale after this amount of time they do not function the same. This could be something else to consider as i know renewing my sensors made a difference to the acceleration.

its a hiccup
its like the theres a dip in power for a split second then off it goes again my car had this symptom from new
but you right it could be the lambders there easy enuff to check with op com when there hot and cold
another thing is the chains with 72k there ripe for changing 🙂

vocky

the cam would need swapping as the vectra B uses a mechanical power steering pump and requires a Hex drive on the inlet camshaft, astra/vx220/zafira do not have the hex drive.

To me it sounds like it might be cam timing, did you get a new chain kit fitted ?

evocarlos

vocky said:
the cam would need swapping as the vectra B uses a mechanical power steering pump and requires a Hex drive on the inlet camshaft, astra/vx220/zafira do not have the hex drive.

To me it sounds like it might be cam timing, did you get a new chain kit fitted ?

thats what i was unsure of ive never taken the end plate off mine so didnt know if the hex was there or not

D-F-A

🙂Hi lads, just finished work and seen your reponses, I think that i mentioned changing the cam over due to the power steering being different. Today I picked up the car from the garage and used it to go to work, 120 mile round trip on motorways, I did what I believe Matt and Evo suggested, in that I try to accelerate easily through the range and see what effect it had. The flat spot wasn't there other than when forgetting for moment , allowed over-run and speeded up quickly then it was there like gangbusters. Also the spanner light and engine management light came on although the car behaved beautifully the rest of the way home. Mechanic said that they had blocked off the ERG but made no difference. I will replace the air filter as suggested here also. Idi Amin would thersensors not show as a fault, I don't know I'm just asking the question? I had a new cat fitted about 23.000 miles ago and I know that a sensor was changed also as the engine management light would come, this when I had just purchased the car. Thanks for all the time you guys are spending trying to help me, it is much appreciated, this forum is rather like another I belong to Club 80-90, I also own a VW bus for my sins..Regards Rob🙂

IDI_AMIN

All above answers could be correct you swapped your engine so possibly the newer engine may need new timing chains timing could be out .engine management light could be caused by lambda sensors a code reader will give you a definitive answer . if you feel you are burning a lot of fuel this is a symptom of sensors not functioning correctly it was for my car. They are all possibilities you just need to eliminate one at a time