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The 98 has been doing great so far in my 4 months of owning it. The issue at hand is whenever it is less than 0 F (-12F today) in the morning the car idles like it has the shittiest cam in the world. It surges to 1200 then down to 7-800 and does this in 2-3 second intervals. When it warms up after about 8 min the idle smooths out at a constant 900 RPM. I have already changed spark plugs and wires which made the car idle perfect. Can it be a throttle body issue only when it gets that cold? it seems like the throttle blade is moving but may not be moving fast enough to smooth out the idle. Would a dirty throttle body cause this slow modulation only in cold temps? Oil was changed (5w30 mobil one) at 49K and it has 50.5K on it now so I know it shouldn't be dirty or old oil. Any input would be appreciated!
The 98 has been doing great so far in my 4 months of owning it. The issue at hand is whenever it is less than 0 F (-12F today) in the morning the car idles like it has the shittiest cam in the world. It surges to 1200 then down to 7-800 and does this in 2-3 second intervals. When it warms up after about 8 min the idle smooths out at a constant 900 RPM. I have already changed spark plugs and wires which made the car idle perfect. Can it be a throttle body issue only when it gets that cold? it seems like the throttle blade is moving but may not be moving fast enough to smooth out the idle. Would a dirty throttle body cause this slow modulation only in cold temps? Oil was changed (5w30 mobil one) at 49K and it has 50.5K on it now so I know it shouldn't be dirty or old oil. Any input would be appreciated!
You really need a scanner to monitor the parameters in real time. Any codes?
No codes. I do not have a scanner for real time at the moment. I am in the process of buying HPtuners. I was just curious if others had these types of problems before.
Why you wasting your money on HP Tuners ???…will you be doing any tuning ???…it is not really a tool that can read DTC’s from ALL the cars modules…to diagnose effectively you need to look at inputs and outputs from those modules and have bidirectional capability…save your money and get this cheaper Autel…BTW, I’d be looking at your ECT sensor…you can also look at TPS%…data PID should be less than 10%…if over 10% the TB may be dirty.
I will be doing tuning. I would like to get headers and an intake in the spring when its warmer to install them in the driveway. Preferably would like to tune with HP tuners but if it cannot help me with all module diagnoses then I may be adding something like the above as well. Thanks for the info. I will try to check the data you mentioned.
@C5 Diag Hey Rob, could this possibly be a dirty MAF? Sounds like the OP has an over rich condition. But this is all guessing until he investigates further.......
Mike, with the car running poorly cold I’m thinking skewed ECT sensor…sometimes the PCM will plug in a value “substituted value” just to keep the car running…in “Generic” OBD2 the PCM can not substitute that value if you were to go into the “Enhanced” side of the scan tool…he can check the TB to see if it’s dirty.
Cold Weather Cold Start
