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reduced engine power

 
jnusca
I love my Chevy Chevette!
Posts: 1
Joined: 12/11
Posted: 12/23/11 05:59 PM

my 1997 c5 intermitently goes into reduced engine power with the message to check traction system as well as the engine light coming on. if i stop the car, turn off the engine for 1 minute and start it up again, the problem goes away but can come back at any time. the reduced power limits the speed to about 35mph and is dangerous in a highway environment.
i have had the car at a gm dealer who put it on an engine analyzer and showed codes p0327 and p1188 stored in the computer.
the dealer said i may need either a throttle actuator module or accelerator pedal.
a tac module was ordered in august (gm part 19245405). none are available; no indication from gm when they would be available. now the dealer is advising that the existing module needs to be taken out of the car and rebuilt as the part is not available from gm.
if i can't fix this problem, the car is not safe to drive and it has only 14,000 original miles  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/24/11 06:47 AM

lets take a look at the trouble codes first..

P0327 - Knock Sensor Circuit Low Voltage

P0327 - GM

Description
Knock Sensor Circuit Conditions

Cause
No CKP, ECT, MAF, TP or VSS codes set, system voltage 10-18v, engine speed 1000-5000 rpm, ECT input more than 153°F, throttle position from 10-15%, engine load over 45%, maximum spark retard less than 15°, and the PCM detected a Knock sensor signal that was within a calculated average voltage range for 10 seconds

you may have not gotten a ECT engine coolant temp sensor code.. but you did get an Engine OIL Temp code.  that MAY cause the computer to  remove power to protect the engine.. .



P1188 - EOT Sensor Circuit High Voltage

Type Powertrain

Description
Engine Oil Temperature Sensor High Input Conditions

Cause
No PCM codes set, engine running 30 minutes, then the PCM detected an EOT sensor input of less than -23°F for 4.5 seconds


guess what...  you probably don't need a throttle module parts..   its hard to tell from this far away.. but if these codes are set...  your car will do exactly as you describe ..  won't go faster than a snail...

do you own a scan tool???  do you want to fix this your self..

you might first try replacing the offending sensors..  the oil temp sensor.




this is the detonation sensor..   these may not be the ones for your car..  yours may be much smaller and there may be two



without a scan tool...  and you might be able to use the onboard system to read the data stream.. as is done on caddys..   try pushing the OFF and Warmer buttons at the same time on the heater control panel with the key on..   hold both for 5 or 6 seconds.. when all the lights on the dash board come on.. let go..  most of my work is on earlier C4 models..  not the C5s.. but i understand how the systems think..  more to come...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/24/11 07:10 AM

lets look at the knock sensor info

http://www.autozone.com:80/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80cb3f88


the 5.7 motors show the knock sensors under the intake.. the 6.0 and 6.2 motors show them on the sides of the block..

0996B43f80202798

this is why you need a scan tool... but i would change the OIL TEMP SENSOR first.. as that might be the ONLY problem..  

the oil temp sensor could also have a loose connector pigtail or a bad pigtail wire where the wire is broken inside the insulation just from being wiggled by the air rushing by..  it does happen...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/24/11 07:35 AM

here is the info on the OIL TEMP SENSOR.   but it shown for the 6.0 and 6.2 motors.

http://www.autozone.com:80/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80cb3f2a



The engine oil temperature sensor is a thermistor that varies in resistance as the engine oil temperature changes. A low engine oil temperature produces a high resistance at the engine oil temperature sensor. A high engine oil temperature produces a low resistance at the engine oil temperature sensor. The instrument panel cluster (IPC) interfaces with the engine oil temperature sensor via a discreet signal circuit and low reference circuit. The IPC applies 5 volts to the engine oil temperature sensor through an internal input resistor that is connected to the signal circuit of the engine oil temperature sensor. The internal resistor in the IPC measures the voltage and calculates temperature. The engine oil temperature range is between -40 to -165°C (-40 to +329°F).

this is on the bottom of the oil tank... but i don't think that your 97 has that.. but i hope i am wrong..

0996B43f80202f37


Testing


Ignition OFF, disconnect the harness connector at the engine oil temperature sensor.
Ignition OFF, test for less than 1 ohm between the low reference circuit terminal A and ground.
If greater than 1 ohm, test the circuit for an open/high resistance.

Ignition ON, verify the scan tool Engine Oil Temperature Calculated parameter is less than -10°C (+14°F)
If not, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the IPC.

Ignition ON, install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool Engine Oil Temperature Calculated parameter is greater than 150°C (302°F).
If not, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.

If all circuits test normal, test or replace the engine oil temperature sensor.


this IS where i would start... instead of the knock sensors...

if the computer thinks the OIL temp is way below ZERO.. it will back off on the power as COLD oil is really hard to pump...  
 

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/24/11 07:41 AM

oh.. the pigtail connector for the oil temp sensor is duralast #254 at autozone..



if its at the bottom of the oil tank...

replace the pig tail first..   i would bet the wire is broken right at the connector..  does not matter which way the wires are hooked up...  there is 5 volts on one.. and what ever the resistor lets through on the other..  

once done.. clear the codes and take it for a test drive..  

please post how it goes...

if your dash does LIGHT up when you push the OFF and Warmer buttons for 5 seconds..  do so without touching the brake pedal...   codes will show up on one of the displays...    post if this works.  i don't see the chart i use for caddys... where the climate control buttons can be pushed to access the different sensors...   the warmer button may be red above a blue button or an up arrow..    

i hope this helps...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/24/11 07:59 AM

oh.... and i hate to change expensive parts first..  you might be able to fix this with just the oil temp sensor pig tail for under 20 bucks and some elbow grease..

please.. pick up if you don't have a set..  of good wire crimpers similar in shape to channel lock 909 .. so it makes a DEEP dent in the crimp connector..  not just a squish flat..   you will also want to pick up some shrink tubing..  most parts stores sell little packages of it in 3 to 6 inch sections.. so you can slip it over the wire before you do the crimp. then shrink it..  

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