# HELP! Stanza Surging/Bucking at High RPM



## tinaslynn (Mar 31, 2006)

Hi All!

HELP!!!! OK, here's the specs:
'90 Stanza
Ka24E
M/T

I'm at wits ends now with this problem. It started about 2 years ago intermittently.. but now it's every time I drive.
When at high rpm, say around 2800-3000 (not sure as there's no rpm gauge), the engine will start surging up and down.. or let's put it this way, can't go over 55mph on the hwy!
Starts fine, never dies or acts like it's being cut fuel, the rpm's drop and rise at a constant rate.
It also bucks on acceleration and deceleration...
Before checking the ECU, I cleaned the intake out, it ran fine for about 3 days, back to surging, took the IACV off, cleaned, ran fine for about 3 days, back to surging.. REPLACED the IACV, 3 days good, then back again.. so I went to the ECU. 
The first codes it gave me was the IAT and MAF (which isn't very old) and the VSS (speedometer has never worked). Then it never gave me the MAF and IAT codes again after the first test.
Ok, so I replaced the MAF, bypassed the IAT with a resistor (it's hooked back up now) and coil.. also cleaned the distributer cap and rotor..
STILL SURGING!
I get NO codes (other than VSS still).. have reset the ECU several times, and still get nothing.. 
FYI: Distributor was replaced after this started as I first thought it might be the pickup.. not only once, but twice to make sure I didn't get a defective distributor.. 
(Also, within 50k miles, replaced O2 and TPS)
Where do I look now? What else would cause this.. it's like the ECU goes into Limp Mode.. the idle seems fine (it did idle high but went down after putting Seafoam in it), with the new MAF, it has a little more power, but I still can't get the rpm's up without it bucking like a bronco.
What now? I have dished out so much money and nothing..
Fuel injectors? Fuel pump? Hoses? Please someone give me some ideas on where to go next!!!!


Thank you!!
Tina


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## StanzaBonanza (Feb 3, 2007)

Check the fuel pressure and filter. Can it free-rev past 3800 RPM?


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## 91yrsold (Apr 26, 2007)

Sounds like you just need to shift....
Joking aside check your spark plugs as they should tell you whats going on in the cylinder. I think Bonanza is right it sounds like a fuel issue. Check to see if the spark plugs are extra crispy, if so its probably fuel cut off scenario in that cylinder.


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## tinaslynn (Mar 31, 2006)

Thanks guys... just came in from working on it again.. still no resolution..
there is a fuel mixture issue as I can smell it.. plus I'm burning fuel out the tailpipe.. replaced some hoses and rewrapped the intake air hose.. I have no way to check the fuel pressure.. no free rev.. even in neutral, it revs up and down at high rpm.. messing with the fuel injectors seems to make it stutter a bit.. I'm still at a loss.. I've had this car torn down to nothing and put back together and this is one issue that has me stumped LOL
Next will be to pull the injectors and check the orings.. I think I may have a leak on #1 cylinder.. and possibly get a used pressure regulator and try that.. the fuel pump and filter are both fairly new (under 20K miles).. but alas, aftermarket fuel pumps are crap anyway... :lame:

Will keep looking.. or banging my head on the hood until it tells me what's wrong with it...


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## 91yrsold (Apr 26, 2007)

It sounds like you're on the right track but I still didn't see you say you checked the spark plugs. These will give you insight into what's going on in the cylinder itself during combustion. If you do have a leaky injector it would be the opposite of the crispy plug I mentioned earlier and instead should smell like gas when you remove it. This is much simpler than tearing into the injectors and then realizing they were fine, although it does sound like an o-ring on the injector going bad could cause all this. If this doesn't help try dialing back the fuel pump because if its new who knows if you created too much pressure in the line and blew the o-ring.


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## tinaslynn (Mar 31, 2006)

Thanks for all your replies..
I am STILL at a loss on this.. the car developed some other issues which had to be taken care of..
In the last couple of weeks, replaced the fuel pressure regulator, removed, cleaned, resealed the intake manifold, replaced cap/rotor/plugs (plugs were all equally grey), replaced valve cover gasket, changed oil, checked hoses, etc.
Car is running fine now but I STILL can't go over 55 mph without the engine revving thing.. it doesn't cut off, hesitate, choke out or anything. It's a steady rpm up/down at high rpm/speed. Today I heard a distinctive fuel knock (but this was after getting fuel, but I ALWAYS use Chevron fuel, no cheap crap in my car) and it's a tad bit hard to start.
It still have what I call a normal hesitation on acceleration, especially in 3rd gear, but it has always had a slight hesitation there. It isn't bad enough to call a problem.. the problem is I CAN'T DRIVE 55!! 
HELP!!!!!!!!!!
The only thing I know to do is check the wiring to the fuel pump perhaps? (pump is fairly new) I got no codes, no c/e light, nothing.. just a bucking bronco at about 2800 rpm.. but it does it in neutral as well, not just driving..

Any other ideas???

Thank you!!:wtf:


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## PapaCap (Dec 8, 2007)

I'm a bit late to the party, but I thought I may chime in. I'm not sure what you mean by 'surge' or 'bucking,' but if you mean what I call bogging, particularly under load, that is a sign of the engine being out of time.

These cars are notorious for the return timing chain guide to disintegrate, causing it to jump a tooth or two. It causes these symptoms.

The easiest way to check time is to pull the valve cover and harmonic balancer off. Set the motor to TDC. The camshaft and crankshaft keys should be pointed to 12 o'clock when the motor is at TDC. Basically, the keys must be pointed in the same direction. If one is off, the motor jumped time.

If you've checked that out, have you done a compression check? Just to see the health of the motor. Good luck with it.

PC


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## tinaslynn (Mar 31, 2006)

Thank you for your reply.. I have almost given up on this thing.. I did replace the timing chain guides with the new metal ones not long ago.. and also replaced the distributor twice since this started. It is like a bucking while driving similar to when the pick up in the distributor is oiled or dirty. It idles up and down as well (as from the posts above, yes, have replaced everything associated with that).. I can drive fine as long as the rpm's are kept low.. and I have a fuel knock as I have to shift in low rpm's.. it's had so many other issues (ie spindle bearing eating up the cv axle twice and destroying tires in the last year), so this has been on the back burner.. I've just been driving on the back roads a lot LOL


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