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Motor cuts out @ high rev


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barellies's Avatar
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June 14th, 2011, 8:51 AM   #1  
Motor cuts out @ high rev

To make a long story short, I have a 97 Venture with a 3.4L I bought it cheap. I did the head gaskets and the intake among other things along the way. I'm not that familar with anything on the engineering set up of these power plants. The motor starts and runs well it seems but if I rev it very high (In park, rpm unknown) the motor cuts out intermitently until I back off a little. Can someone tell me if there is some sort of control within this system that may be causing this to happen or is there something wrong? I've checked everything it seems. <!-- / message --><!-- BEGIN TEMPLATE: ad_showthread_firstpost_sig --><!-- END TEMPLATE: ad_showthread_firstpost_sig -->

 
rjsp's Avatar
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June 20th, 2011, 9:02 AM   #2  
Did you give it a tune up along the way?... Particularly the fuel filter? Plugs, wires, clean throttle body, clean iac, air filter, pcv valve, also check for weak vacuum lines that can collapse under high demand??? Start there. It may need some code reader, computerized diagnostics.

 
barellies's Avatar
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June 23rd, 2011, 6:33 AM   #3  
Yeah I haven't had much luck, I have done all that. I am in the process of rechecking the vacuum hoses and fittings. It doesn't appear to have any codes to read, at least the check engine light or service soon light isn't displayed.
AIC ??? I'm having a brain fart...


Last edited by barellies; June 23rd, 2011 at 7:46 AM. Reason: addition
 
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June 26th, 2011, 8:01 AM   #4  
There must be some sort of speed limiter devised into the system that will not allow the motor to over rev while in park or neutral because when I went on the highway with it and mashed the accelerator it dropped to a lower gear, the RPM went way up and it didn't even burp! Away we went! Huh?

Now if I can get all the electrical problems figured out... IE: the fuel gauge the ABS & seat belt idiot lights are on and all the interior lights don't turn on. I need a good schematic.

 
my3girlz's Avatar
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June 26th, 2011, 9:27 PM   #5  
Is the check engine light on? if so u may want to get it scanned from an auto store or get one of your own.... In any case i will take a pic of the schematic i have from the manual and send it ur way. Send me pm and ill send it to ur e-mail..... i cannot link an attatchment here.

There is also an "IAC" or idle air control valve that can be tested.... It is located on the throttle body, and a scan tool is required for complete testing of the iac valve and circuits. However several tests can be performaed to verify operation:
1. when the engine is started cold the iac should vary the idle as engine begins to warm. Allow to warm the place under a load ( by placing in gear, turning on the a/c and operate the power steering....the idle should stay the same or increase slightly, if the engine stumbles or stalls or if there are obvious signs that the iac valve is not working stop engine and continue test.
2. disconnect elect connector use an ohmeter and measure resistance across terminals 1 and 2 of the iac valve (the top 2 pins) and then 3/4 the resistance should be about the same on both sets "approx 40 ohms". If one or both indicate an open circuit replace the valve. If good have valve diagnosed by dealer or auto repair shop.

Per manual....?


Last edited by my3girlz; June 26th, 2011 at 10:24 PM.
 
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