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Bad Idle & Surges under load ( hardly any power ) Any Ideas??

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miller81

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id say airflow meter,if it isnt revving past 3k and bad idle thats what i would be checking first
 
M

miller81

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im pretty sure it will only go on one way,you dont have to mark it..at least thats the way it is on the cars i work on,you normally only have to mark where you adjust it
 
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I have now replaced the dizzy & airflow meter

still not working right.

I have a replacement ecu on the way

just wondering, when i did the fuel pressure test the guy that did it said its all good but i didn't see the reading on the gauge. does anyone know what the pressure should be?
 
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Did you check your timing and also did you check to ensure that the tps voltage on the throttle is where it should be? The tps on closed throttle should be 0.45V or thereabouts and on WOT should be 5.0V or thereabouts. This can be checked when the car is not running but the key ignition is switched to the ON position and the voltage pulled using a voltmeter/multimeter. The tps should have two screws holding it in position, lightly slacken both and turn to get the right reading for closed throttle and thentighten and recheck that it is good, it car vary quite easily. Then once it has a proper reading check at WOT again and once good that can then be eliminated from the equation. Cost is free so best to check it before you pay to check other stuff.
 
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Did you check your timing and also did you check to ensure that the tps voltage on the throttle is where it should be? The tps on closed throttle should be 0.45V or thereabouts and on WOT should be 5.0V or thereabouts. This can be checked when the car is not running but the key ignition is switched to the ON position and the voltage pulled using a voltmeter/multimeter. The tps should have two screws holding it in position, lightly slacken both and turn to get the right reading for closed throttle and thentighten and recheck that it is good, it car vary quite easily. Then once it has a proper reading check at WOT again and once good that can then be eliminated from the equation. Cost is free so best to check it before you pay to check other stuff.
Year someone else mentioned that to me the other day, said i needed a multimeter to test it, so im glad that was in the post today when i got home from work, and thanks for the how you go about it part as i was unsure what to do. by the way what does WOT stand for?
 
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I have swapped the ECU and still no change.

When i got the ignition timing tested i also had a diagnostic test done and that cam back ok 55 ( five slow & five fast flashes ) that means all good im told
 
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Year someone else mentioned that to me the other day, said i needed a multimeter to test it, so im glad that was in the post today when i got home from work, and thanks for the how you go about it part as i was unsure what to do. by the way what does WOT stand for?
TPS reads exactly 4.47v
 
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4.47V at what WOT or at closed throttle? This should be done when the key is only in the ON position but car is not started.
 
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Wait throttle at closed position and reading 4.47V? That should never be, it should be 4.47-5.0V on WOT. Maybe you are reading the wrong wire, maybe the positive feed on the TPS. Try when you are reading the voltage to open the throttle and see if the voltage fluctuates, if it does then you have the right wire.
 
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The other day i put a very concentrated dose of injector cleaner in which has seamed to make a slight difference as now i can get to 100kph in under 20 sec:rotfl: , and got the ignition timing adjusted. as the injector cleaner made a slight difference i thought it might have been bad fuel pump as the test showed about 28psi

Have just changed the fuel pump with a walbro 255 , well it has made stuff all difference, next thing to test is water temp sensor ( mechanic recommended it ) and at least i now have good fuel pressure for future mods

also how much would you pay for a factory fuel pump done 60k?
 
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Wait throttle at closed position and reading 4.47V? That should never be, it should be 4.47-5.0V on WOT. Maybe you are reading the wrong wire, maybe the positive feed on the TPS. Try when you are reading the voltage to open the throttle and see if the voltage fluctuates, if it does then you have the right wire.
I made have made a very silly mistake when testing this, ( ive only been playing around with cars for a few months :rotfl: ) i was looking on another website which showed the TPS unplugged, i was testing it unplugged.......
which would break the circuit, i tested it plugged in by inserting the tester wire down the back of the plug wire ( middle one with the ignition set to ON) got a reading of .613 V and at the same time noticed a bit of calcification on the plug as well.

http://www.nissansilvia.com/forums/index.php?showtopic=223078

After adjustment, from throttle closed position reading 0.613v adjusted it to 0.450v, (WOT throttle only reads up to 3.980v after adjustment) and man its tricky to get to the bottom screw, why didn't they use bolts?? ........
Still no change. (WOT throttle before adjustment read 4.47v)
 
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Yeah the way it works is that when you adjust one it changes the range for the other as well. What is your base timing set at? The base TPS voltage should be .45V and WOT 4.5-5V so if you can't get that range then I suggest replacing it to eliminate a problem. I don't think they are that expensive and can be ahd in a scrappy for next to nothing. Also, if you can borrow a freind's MAF and swap it to see if it makes a difference to eliminate that as well, seeing that the car remains under 3000rpm sounds MAF related like it is in limp mode when the MAF is unplugged. Just try things to eliminate stuff and also looks for any broken vacuum lines and boost lines even though you may have already, both on the intake and on the intercooler setup.
 
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