dereklicon

Im getting real desperate here, its been two weeks and we still cant get this thing running right. Any help would be greatly appreciated.

Im going to try to give as much info as possible.

We changed the manifold gaskets and now we have all these problems.

It sounds like the timing is really retarded, sounds like it has a cam but its the stock cam. the engine is popping through the intake, and it surges somewhat at idle and part throttle. It also dies at a stop sometimes. When you shift 1-2 manually though it has plenty of power and revs up well past 4000 rpms. Shift to drive from park after setting base idle and it dies unless you give it gas. Hard to start without throttle.

Keep in mind the car ran OK for 10 years besides some power loss and a small miss before we did anything to it. it did NOT pop through the intake and never I saw all these other issues so we started to fix them one by one. It never died at lights or surged. Now we replaced the gaskets and did it again to ensure we didnt have any vaccum leaks. It is a stock TPI car.

I fixed the tachometer, before it used to read way off, I bypassed the chip and installed the two 100k ohm resistors and now it reads fine.

I fixed the oil pressure gauge, the two prong plug wasnt plugged in when I looked at it and I plugged it back in and it seemed to fix the oil pressure gauge.

I also fixed the temp gauge. it was missing the sender on the side of the block.

The radiator fan wouldnt turn on. Needed a new fan motor and wiring was shot so I wired it in to the blower switch and now it comes on automatically with the key on.

The car had a EGR that wasnt functioning at all, the vacuum port on the EGR was plugged up and the port on the throttle body was leaking. We plugged it, and blocked off the EGR port. It made no difference in the way it ran.

The MAF has never worked. It dies immediately when we plug it in. I know some of you are saying "change MAF" but it ran just fine for 10 years with no MAF. MAF is a luxury that we cant afford at the moment after everything else we spent.

We bought a new CTS. No difference.

We bought new 19 lb injectors from South Bay. No difference.

We torqued the manifold in perfect order and torqued it to spec. No difference.

We bought a new IAC and set base idle. Paper clip to A+b ports on ALDL, key on, unplugged IAC, turned engine on, set base idle to 600, turned engine off, took out paper clip, plugged IAC back in, computer moved idle down to 550-500 and it mostly dies in drive unless you give it gas.

We adjusted the TPS and tried moving it from .54v to .60+ to see if there was a difference. None. The voltage was moving erratically while it was running, so, We bought a new TPS and when I first installed it it seemed to run a tad different. No more surging, and it didnt sound super retarded anymore.... I took it out for a test drive and it still died at stop lights so I tried adjusting base idle and BACK TO SQUARE ONE, idles erratically like it has a cam still even after readjusting TPS. Double triple checked base timing, STILL at 6*.

Bought a fuel pressure tester and the FP is consistently at 45 PSI.

Fuel pump has been changed already.

Base timing is set at 6*, wont run at 0.

there are NO vacuum leaks, sprayed whole intake with brake cleaner. No difference. I blocked off PCV tube, booster hose to see if they were causing a vacuum leak, no difference.

We changed the distributor, new coil, new ICM, new cap, new rotor, NO difference.

There is no apparent misfire. Plugs are black and sticky but they dont appear to be causing any issue, like I said there is NO apparent misfire. As far as I can recall I have never heard of or seen bad plugs causing a pop through the intake after 8 years of working professionally in the field.

I checked all the injector pulses with a Noid light. They are all receiving the pulses from the ECM. just fine.

Please help us. Thanks

OrangeBird

iTrader: (1)

I know it sucks to dump cash into stuff you think doesn't matter , but I believe the MAF matters a bit more than your giving it credit for , especially since you say you now have a different chip in the ECM ?

You have not mentioned two things , unless I've missed them ;

#1 Compression test readings on all 8 cylinders

#2 Manifold vacuum as displayed on a vacuum gauge

I believe your answer will be found in one or both of the above tests ....

Drac0nic

As a crazy newb question you did disconnect the tan/black wire at the dizzy before setting timing, correct?

Have you validated TDC to see if the balancer slipped?

Lastly, I would be looking to diagnose for timing chain slop. You can end up with some really erratic results if that's the case. Also if it's a 92 you're into a roller engine not a flat tappet which reduces the risk of a flat lobe.

Colt

It sounds like your harmonic balancer is shot and the timing mark moved. Look at it carefully and see if there is any issue.

The give away for this is that you took the intake off and had to retime the engine. This is typically when this issued is raised.

dereklicon

Yes, I unplugged the EST wire when setting timing

I stabbed the dizzy properly at TDC, 0* after the intake valve closes at #1. I always take the valve cover off when installing a dizzy.

The car we are working on is actually an 86 Z28.

My car is a 92 RS however so yes you are right but my car has zero issues lol.

As far as manifold vacuum, we did not end up checking that or compression.


As for an update..... I tried to drive the car around after setting base idle and TPS a billionth time. I drove it around for about 20 minutes and now the engine is now making horrible knocking noises. I removed the valve cover while it was running and there was barely any oil coming out of the pushrod holes on the rockers. The head also had what looked like sand and black sludge.

We just did the oil change last month. I did notice the black oil but it was running. We have been running it hard lately. Maybe the motor was already on its last leg and revving it pushed it over the edge.

It could be coincidental.

what a disappointment.

Were getting a vortec 350, carbed.

Colt

Did you ever check to see if the balancer separated?

Drac0nic

The 350 Vortec is a good idea. Pull the other side and look for loose pushrods. I bet your timing chain is junk and you probably are down a lobe or two on the cam. If the noise is a tapping noise I'd look for a loose push rod. If you're on a budget the other option would be to try and jam a cam and timing set in and flush the motor out.

mhou91z

Sorry to hear about your problems..
Your problem lies in the A: ignition wires in the wrong order, two wires are swaped...
B: Distributor is stabbed wrong, one cylinder off.
Anytime you get the backfire/pop through the intake its crossed wires or distributor stabbed wrong..
Guarantee you.!!!!!
Its easy to mix up the wires done it myself several times and same result.
You should have a third person help you count off the plug wires and verify the correct instalation. Reset your #1 TDC and triple check the rotor is pointing directly to the #1 terminal under the cap. Double check you are reading the correct firing order because you got two reversed. Good Luck..

ex-x-fire

Try twisting the distributor to see it runs better. Ain't gonna cost ya nothin.

dereklicon

UPDATE:

I did not stab the dizzy incorrectly. Firing order was on point. Wish it was that simple lol. Timing was at either 4* or 6* BTDC. I have stabbed many dizzys. maybe a 30 min job for me at the most

To continue where we left off, this is what I found. Several things. Valve cover was off and there was little to no oil shooting out of the rocker holes while revving motor. Motor began knocking and ran worse the more we ran it. Found sandy sludge in heads.

I pulled the motor out. took me about 3 hours. From the top with the tranny. It was really easy.

Did some inspecting of the motor. I have not taken off the timing cover yet, however the balancer has not slipped. with the heads off you can clearly see the piston at TDC with the mark at 0 so I know it wasnt a balancer. When I inspect the chain I will update again, and will be rebuilding the 305 in my apartment for fun. it had 416 castings on it anyway!

SO when I took off the heads, guess what I found. First we had TWO bent pushrods.
Second, the passenger side bank head gasket had signs of severe overheating and cyl # 4 & 6 were crossing over. you could see the black soot between the cylinders on the head gasket. a simple comp. test may have revealed the loss of compression.

We already have the vortec 350. Going with a 600 cfm carb and hooker headers. stock motor for now later well throw in a cam.