Are there any plugs that could have been left unplugged? We just had the timing belt idler pulley grenade and bend the valves. Professional reworked the head. All valves are new and we are not getting any misfire codes. We are getting p0107 map sensor code. MAP sensor checks good as voltage varies between 4.8 and 1.2 volts when throttle is opened and closed with engine running When started the rpm goes to about 3000 to 3500 and drops back in a few seconds. The engine runs Great and Smooth. Idles at just under 1000 RPM. Has Lots of Power! Only will not go into 4th gear (automatic) Limp Mode? Codes are p0700, p0107 and p1781. Please Help
The Code 700 is a generic transmission Code and in some cases may relate to Emissions problems relating to transmission performance. Beyond the generic Code, a better scanner will show the specific defect.
The Code 1781 is a hodge-podge of defects. Found a GM TSB on valve seals and valve replacement. It listed (By serial#) a replacement sequence where on some production numbers only the Exhaust valves needed to be replaced, and on others all valves needed replacement. All the valve seals needed replacement regardless of serial#. Perhaps this is a hold-over from your original problem.
The Code 1781 is a misfire Code due to Valve seals. It is also listed as a condition where the Engine Torque signal is wrong. And also a condition where the ECM and TCM are not communicating.. Can't say why so many different problems tied to 1 code.
The Code 107 is as you said is a Map sensor Code. Many makers operate this warning the same way. You are correct that your MAP is probably good. For some reason, the makers blame the MAP for the problems of the devices which report to it. From the O2 sensors back through the throttle positioner and all airflow occurring after the airflow passes the MAP. If the measurements do not meet the settings that are permanent at that "appliance", then a MAP code will show. What you need to do is examine the downstream parts to determine why they do not conform. Even a intake gasket leak will affect the manifold pressure.
SOURCE: Car runs greAt BUT FLASHES LITE PO300 P1781
P0300 is a random engine misfire code. P 1781 is a transmission code, but it refers to a malfunctioning engine speed signal (crankshaft angle sensor). A bad crankshaft angle sensor or camshaft angle sensor can cause the P0300 code. A large list of items can cause a P0300 code, but since you have both, I'd be checking the crankshaft angle sensor and the related circuit. Sometimes, the mounting screws loosen up, which can cause the sensor to not function properly, all the time. Get this fixed, because over a period of 4 to 6 months, this can destroy the catalytic converter in the exhaust system ($$$$)
Charlie
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SOURCE: codes given are p0700 and p1781. Anyone know what these codes stand for? Thanks
The Transmission shop lacks the skills and tools need to do the job. It's best to call around for a shop that has a proper scanner to talk to the TCM computer. The real trouble codes are in there. The best place would be a shop that has a ASE mechanic on duty or the Dealership.
Here what the two codes means:
P0700 Transmission Control System Malfunction
It means you have a trans control problem in the trans computer.
You will need to get it on a trans capable scanner to see what the trans code or problem is.
the P1781 is set during engine start up when the ECM & TCM do not communicate properly during initial power up. It will only illuminate the service light if the condition occurs in 2 consecutive start cycles, but the DTC will be stored in the failure records after the first cycle.
there is a Technical service bulletin for this problem, the number of the TSB is 01575, TSB Date:January 1, 2004
It has to do with engine valve seating problems.
SOURCE: 1989 Chevrolet C1500 with 5.7L V-8. Engine dies
fuel pump is working but when accelerating it doesnt pump enough fuel up to the engine then it will fall on its face if it is a electric pump you may have to drop the tank if it is inside and replace it if it is on the engine replace it thats what is exactly wrong with it
SOURCE: 98 Chevrolet Silverado runs rough at half throttle and past.
try removing the EGR valve and clean inside of it and manifold
Removal & Installation
3.5L Engine
Fig. Timing belt routing and timing marks-3.5L Engine
Fig. Timing belt and related components-3.5L Engine
Fig. Adjusting the tensioner pulley-3.5L Engine
Fig. Measuring the auto tensioner rod-3.5L Engine
Fig. Timing belt routing and timing marks-3.5L Engine
Fig. Timing belt and related components-3.5L Engine
Fig. Adjusting the tensioner pulley-3.5L Engine
Fig. Measuring the auto tensioner rod-3.5L Engine
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There are other codes that should be setting if, the problem is with the valves. P0300 has never been set in the 3 scans that we have done. The engine runs Great. Has plenty of torque and like my Dear Old Dad used to say. You could stand a nickel on the Air Breather ( if they still had those ) and it would stand up with no problems. I will be back to the Scanner today to try and pull up additional info on P0700 and P1781. Thanks!
We found the problem months ago. It was a plug left undone wich es tothe ECM. This was the Temperuture Sensor just below the Intake Manifold and between the Firewall and the engine. You will need to get at this plug/sensor from under the car.
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