I have a 97 Blazer 4x4 that I have rebuilt the engine and trans in. Keep getting a p0300 and i think a p1870 trans component slipping code. Engine doesnt idle smooth it surges between 500-650 rpm. Also surges when in gear with foot on brake pedal. I have replaced all vacuum hoses, the distributor, plugs wires, ECT, IAT, Idle air control motor, TPS, EGR valve, fuel spider, cleaned throttle body, and replaced map sensor. At this point i am starting to wonder if the ecm has gone bad. Have also replaced the fuel pump shortly before rebuilding the drive train. At wits end here, tired of chasing my tail. Any advice would be greatly appreciated.

 

P0300 is almost always caused by a fault in the secondary ignition system: plugs, (should be AC Delco 41-993 gap .060") plug wires, distributor cap & rotor, (should also be AC Delco) and the ignition coil. Low fuel pressure and or excessive leakdown can also cause a misfire: Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off. Worn distributor bushings and or drive gear can cause it too. Other things to keep in mind: If/when the crankshaft position sensor and or timing cover are moved, removed, replaced, or disturbed in any way, the crankshaft position sensor relearn must be performed using a capable scan tool. After the distributor is installed, camshaft retard must be checked and adjusted if necessary with a capable scan tool. Desired spec is zero degrees with a tolerance of +or- 2 degrees. The PCM's on these things are nearly bulletproof and rarely fail.

EDIT: P1870 usually indicates a problem with the TCC, (Torque Converter Clutch) solenoid.

 

I used Delco plugs and wires, installed a new distributor because the bushing went out in the old one after the engine was put together. I installed a new fuel pump just before the TCC went bad and tore up the engine bearings and trans. I rebuilt the engine and trans myself and i replaced the TCC solenoid when doing the trans. The codes show up simultaneously. I have performed the relearn procedure for the crank sensor and not sure what the cam retard is since the distributor was changed since i didn't do it some, my dad did. When ever the miss fire code shows up the trans starts shifting really harsh. Just feel bad cuz its my moms vehicle and my dad and i are both mechanics and we are stumped.He works on chryslers and is not really amiliar with GMs and I am a heavy equipment mechanic and am a bit rusty on the GM stuff.

 

Have you checked fuel pressure and leakdown on the new pump? If so, what were the readings? What make & model scan tool did you use to do the crank relearn? Did it accept the relearn? The same scan tool will access camshaft retard as well. Which DTC sets first? P1870 or the P0300?

EDIT: Have you checked misfire data to find out what cylinders are misfiring?

 

Haven't checked the fuel pressure yet. My dad borrowed the Tech 2 from where he works so we could do the relearn when we first got it running. I don't believe he checked the retard when he did the new distributor but i wasn't there. It did accept the relearn when we did it.As for the codes the P0300 is the only active code when we scan it when the light comes on the p1870 is inactive, but in order that code to be active the conditions have to reoccur within two consecutive start cycles. We clear the codes and they come back under heavy acceleration, but it isnt a consistent thing to duplicate. When the miss fire code shows up there is no feel that it is miss firing. It doesnt stumble or hesitate. It has an inconsistent idle when sitting still in both park/ neutral and in gear. When driving it will idle at 35 mph on its own no need to touch the go pedal. Runs fine when driving above that speed. I am just trying to get some ideas in what to do. I will do the fuel pressure test and relay the results.

 

Get your hands on that tech2 again it will access camshaft retard. 15 minutes to check and adjust it. The name is misleading, should be called "camshaft position sensor alignment" as far as I'm concerned, cuz that's what the adjustment does. It's done by rotating the distributor slightly.