No idle, knockin, hot engine WTF!!!

Mr. Rustypwnz

Advanced Member
Jun 1, 2005
1,761
63
69
indianapolis/ valdosta ga
Ok, today I fix my brakes, go drive it to put some gas in er, notice a tapping sound, so I pull the valve covers, and two roller rockers came completely loose, bent a pushrod ever so slightly, so I bent it back to perfect, put the stock rockers on to rid the sewing machine noise, put it together, runs the same. So I go drive it around and I start in second, dump clutch, floor it, it bogs down bad knocks some then takes off like crazy, I get back to the house, after 5 mins of driving it wont idle right like before, but the intake is extremely hot, and the rad is cool, very cool, And I have a big arse hood scoop on this thing. Also when its cruisin it pops, like ba, ba, ba, then starts jerkin all over the place at about 2500 and below, when you just tap the gas at this rpm in 4th it knocks to no end, anyway this is really gettin to me, anybody else have this prob? I Have a whole week to fix it, but whats the deal?

mods gt40p heads
ported intake
bcam
65 mm tb
cai
95 gt 70mm mas
lt headers
walbro 255
ud pullies
flowcrappers


any input at all would be nice!!

Josh :SNSign:
 
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You will never get a bent push rod "straight". it will always be bent or tend to bend.

Backfiring out the intake is either a valve stuck open or a lean mixture or spark plug wire(s) connected to the wrong cylinder(s). Check compression on all cylinders and then look for vacuum hoses loose, cracked, or misconnected. Check the line for the vapor recirculation system – it is easy to knock loose and not see it when you connect the air pump plumbing. If the vacuum line for the EGR valve and the air pump are cross connected, some very strange things can happen. Check the mass air flow electrical connection and see that it is tight, the same goes for the fuel injection wiring harness connectors up on top of the manifold near the firewall.

Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Use a vacuum gauge connected to any convenient spot on the intake manifold. Run the engine at 1000 RPM & look for 18-21 inches of vacuum with a steady needle. A problem intake valve will make the vacuum gauge needle sweep 5-10 inches.

Lean fuel mixture breaks out into several sub categories:
A.). Vacuum leaks
B.) Air entering the intake without passing through the MAF.
C.) Failure of the MAF, BAP/MAP (Baro or Manifold Air Pressure, same sensor, different name), ACT (air charge temp), or ECT (engine coolant temp). These should set a code in the computer.
D.) Leaking exhaust gases from EGR valve at WOT or EGR opening when it should not be open.
E.) Poor fuel delivery due to bad fuel pump, clogged filter or bad fuel pump wiring. Look for low pressure or fluctuating pressure. Standard injector pressure is 39 PSI at idle, with the vacuum line disconnected from the regulator and capped.
F.) Clogged fuel injectors.- see the cylinder balance test below
H.) Fuel injector wiring problems causing injector not to deliver rated flow.
I.) Computer problems: (computer problems are not common like sensor problems)
J.). ROM has bad data in fuel or timing table. This should also set a code in the computer.
K.) Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one. Use a noid test light to test the injector wiring & injector drivers,
L.) MAF calibration off or mismatched to injectors.
M.) ACT or ECT bad. Sometimes the sensors will be off calibration, but not bad enough to set a code. If they falsely read too high a temp, the engine will back off fuel delivery.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure

A hot block and cool radatior sounds like a water pump that isn't working or a thermostat stuck shut. The water pumps for engines with a serpentine belt rotate in a different direction than a water pump meant for use with a V belt. Are you sure that you have the right water pump and the belt is routed correctly?
 
ok, I can rule alot of those out, Im puttin a new rad in today anyways, and ill check the tstat, and swap in a new act and clean the iac and the mas. there are no bent valves, new crane springs, and I swapped the rollers out for the stock pieces last night. The pushrod I bent back I put it beside a good one and bent ti back then rolled it on a smooth straight table so it should hold for now. Ill pull some codes also. I meant to put that its like doin the buckin thing, stumbling not backfiring, at around 25-24ish and below.