I've been having performance issues since having a rebuilt 350 installed in my formerly 305 tpi camaro. Been doing lots of trouble shooting and I am at my wits end and have no clue what to do now. The problem is that i am having lots of hesitation issues at prt throttle, lack of power, and am running too warm (i.e 220 to 230 at idle and on the highway when i previously never got over 200*). So frustrating.

I noticed that my coolant was dark green and has an oily film on top. My engine oil dipstick comes out full and with transparent brown oil on it (like normal). No white smoke on start up. I am slowly loosing coolant somewhere. Now when the engine is hot my overflow tank is at the cold mark. It could just be due to getting rid of air pockets as I have drained and refilled with a new radiator and 180 stat.

As far as hesitation it just feels very flat under acceleration, like its starving I could easily bark the tires in 2nd gear with the 305, but cant seem to get the 350 up to speed as quickly. Feels "anemic" and sluggish.

Also I sometimes (1 out of 7 starts or so) get a click and nothing, then the same, then a start. Even when it does start right away I hear a ticking noise for a few seconds that either goes away or I just dont hear it any more. The flex plate is a new aftermarket piece from rockauto.com.

I replaced my coil, cap, rotor and sprk plugs with autozone parts (i think the coil was Wells) and plugs are delco. Wires are 8.8mm moroso.

I have a holly afpr, fuel psi set to 48 psi, a new fuel filter, and reman'd 22# injectors from rockauto.com.

Air filter is k&n and recently cleaned.

ECM is correct application (91 350 tpi with a/t).

Timing is set at 6*.

TPS voltage is .54 at idle and i can smoothly get it to 4v with WOT.

Coolant is approx 70/30 with distilled water.

I have a aldl cable on the way so i can run diags with my laptop.

This is what i have narrowed it down to:
1) Leaky intake or head gasket causing the running hot (even on the highways- and yes the airdam is there and bolted up tight), and causing the coolant loss. Its possible that my coolant level in the resorvoir is lower b/c of burping air out and some evap with summer heat. And maybe this is affecting compression in a way that im not getting all the power out of my 91 octane.

2) Or this is due to running lean and not cooling due to lack of enrichment. This would explain the hesitation too. At this point I have narrowed it down to a bad injector or to a faulty cts or o2 sensor.

3) I dont know what a bent/cracked flexplate may cause, but maybe this is whats causing my starter problems and maybe its affecting my torque converter and/or tranny. Both were rebuilt and replaced last summer. Havent changed the fluid since the rebuild.

Someone please help!!! What could the solution be??? It runs but doesnt run like a gem. This really sucks and frustrates me badly.

 

Sounds like severely retarded timing.

What timing cover, and what balancer, are you using? At what "o'clock" is the stationary side of the timing mark, in relation to the crank center? Chrome aftermarket timing cover and stock balancer?

The start problem sounds like a defective starter or loose battery cable. Whole other issue. Work on one thing at a time; either repair the bad connection at the battery and/or replace the starter, or go to work on the driveability problem.

There are alot fewer blown head gaskets in the world than there are cars with mystery coolant leaks. Probably by a factor of 1 out of 50, or less. Use some logic.... it's near about impossible for water to get into the cylinders (15 psi) without cylinder pressure getting into the coolant (1200 psi or more). Sounds like that's not happening. Forget the head gasket. Your mystery coolant leak is your water pump front seal or head bolt threads.

It's not impossible that it could be a lean condition. What's your fuel pressure WHILE IT'S ACTUALLY MALFUNCTIONING? (not just sitting in the driveway idling with the line disconnected)

 

1 problem at a time:

1)...just checked resistance at my injectors and all are at 17.4-17.8

2) just checked my coolant temp sensor and get no resistance what so ever. Been trying for an hour to get a read. The connector read 5 volts (as it should) from the ecm but the sensor should read 1.04 kohms and i cant even make a connection.

3). I set the timing to 6 a couple weeks ago. will recheck.

4). The balancer is aftermarket stock. Re-used cover from the 305. I dont know the stationary side in relation to the crank. Havent looked at that yet.

5). I noticed today that when i popped the hood, i had a few bubbles coming from the return line into the resorvoir. Not boiling. Just bought a new cap a week ago. I think this is air from pockets and I think I am still de-scaling and cleaning the inside of the block with the coolant. I think you are right about forgetting the head gasket. It was just a worry on my mind.

6). I recheked the pressure at idle with the line disconnected and plugged. Sitting right at 48 psi during idle. I havent figured a way yet to monitor the pressure while driving. Maybe i can snake the guage under the cowl and see whats going on. Having a faulty pump is a concern.

The cts having no resistance is also a concern. The cts controls most engine functions on a tpi.

Thanks BTW

 

I think that's giving it a little more credit than it really deserves; but it's certainly involved with the fuel map, especially.

If it's open (very high resistance), the ECM will think that it's like -40° or something, and will richen the mixture greatly. Kind of the opposite of a starving lean condition.

Probably a good idea to replace it regardless, if it's messed up.

 

just replaced the cts. I took it for a test drive. Better. Will let you know how it goes. No more time tonight to mess with it, but i'll recheck my timing tomorrow. Its at the stock timing of 6 now. But I may advance it a bit and see what difference it makes. I'll be bringing this back up to the top probably tomorrow or the next night, so look out for me.

Thanks for your help

 

Are you disconnecting the EST wire when you set the timing?

 

yes i disconnected the est bypass. Had it bang on 6*.

I pulled the old cts and installed the new one last night. So far so good. Although I havent had the chance to give it a true test drive, it feels like some of the problems with hesitation have resolved.

I need to recheck the timing, thinking maybe its budged a little, but wont have the opportunity until tomorrow.

Jeez I have been chasing so many little things to get this engine running correctly.

I checked my old cts resistance. It was like 1.8 ohms. I couldnt get any read on it while it was in the engine, but those little prongs are tough to get to unless you pull it.

 

when U changed your ballancer did you make sure that it was lined up W/ the timing pointer when it was at TDC, GM used 2 diffrent ballancers/ covers on our cars, one had the timing marks at the 12 o'clock position, and another set that was at the 1 o'clock position, the timing will be WAYYY off if a mis-mached set is used....I found out the hard way

 

They used the timing cover from my 91 305 tpi engine. I used a new balancer for a 1991 350. Hope thats not the problem. I didnt do the install so I dont know.

I replaced the tps and the cts with new parts. Runs alot better but this is beginning to feel like a transmission problem.

My rpm's are fluctating under part throttle, but its pretty sold at full throttle. I dont get it. It feels like the transmission doesnt know if it wants to be in 3rd gear vs overdrive.

When I was changing my plugs I noticed that the motor mount through bolts had the nut started but were no where close to tightened down. Its like the mechanic just started the nuts and left it. I was astounded. It was on both sides.

Nosw I am curious if the engine is bolted well to the tranny. It was rebuilt 1 year ago. Just now (after the install) am I having these issues. Would a bad or loose TC lockup switch cause this?

 

bam! 6 3/4" cover set, 8" balancer. That's a problem, yes.

 

Oh crap...are you serious? How big of a pain in the *** will it be to fix this?

 

if you ues a 8" ballencer on a 6 3/4" timing pointer won't the pointer hit the ballancer?....my best suggestion is to get a known matching set

 

I'm pretty sure it'll just show your timing as being wildly off.

 

I would get a piston stop and verify that TDC on the balancer matches the timing mark on your front cover.

https://www.thirdgen.org/forums/tpi/...ght=split+nuts

 

Well I am waiting for an aldl cable for my laptop. I can acertain the timing the computer reads is what my balancer is pointing too easier I think.

Also, I just noticed the timing cover for the 305 is the same as the 350 in 1991 (cloyes #9226).

Are the pointers different??
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Also just noted yesterday that I was in 2nd gear getting up to speed and my acceleration was really flat from 1500 to 3000 and then at 3000 it started to pull. This is intermittent and occures in any gear it feels like.

My TC lockup is working fine.

Ahhh!

 

Its official: I'm a friggin idiot!!!!!!

Holy crap. First of all. This is a 6.75" dia balancer (for use on 305 and 350 engines per sdpc). But I used the keyway centerline as my timing mark when its supposed to be 10* before that mark!

It was my first time to set timing. My neighbor helped me and had me paint that keyway notch in the balancer as the timing marker and using that as 0* i set it to 6* timing. Does that mean I have too much retard or advance?

 

It means you have to set the timing using the groove on the outside of the balancer.

 

Exactly.

According to the manual, the timing mark is 10 degrees before that mark. But the timing mark isnt exactly "marked" is it?

 

So anyway you can find out all my info in a previous thread here :

https://www.thirdgen.org/forums/tech...eed-vader.html


I was setting the timing with the notch machined into the stock 6.75" dia balancer as my timing mark (the "keyway centerline"). I didnt know that the timing mark was 10* before this mark. How do I find that mark?

Should I use timing tape on the balancer? Whats the easiest way to do this correctly?

Sorry for being a moron, but I just dont have that much experience in this area.

 

There is a single groove across the face of the balancer, which corresponds to TDC (zero degrees timing) on the correct balancer/timing cover tab. If you're not sure if your **** is correct, spend the 10 bucks for a piston stop, pull the #1 plug, and follow my directions to verify it is all good. Every motor I build gets the timing cover mark for TDC verified to the balancer before it goes in the car.....one less potential "error".

 

crap.....ok....I'll get the piston stop. I'm tired of chasing these problems

 

Where can i buy a piston stop at? And how do I spin the engine? Never done this before but doesnt seem too bad

 

Clean off the harmonic balancer outer inertial damper ring. Remove the center bolt from the crankshaft. Find the keyway in the hub of the balancer and mark a clean chalk or paint line from the keyway to the outer damper ring. Install the crank center bolt and torque to 60-65 ft/lb. Orient the crankshaft so that the paint line and keyway are aligned with the center of the block deck on the LH cylinder bank (#1 cylinder). Mark a corresponding line on the front of the block, power steering pump, or whatever is adjacent to the balancer outer hub so that you have a rough idea of where TDC is located once the engine is started. Time it to wherever you want from that point (usually 6° BTC is a good starting point).

 

OK....I just checked the timing again to be sure. Turned the engine on....unplugged the est. Timing at 6. Turned engine off but no check engine light. I checked timing with est plugged and I was at 14 or so.

Why am I not getting a check engine light and is 14 degree timing (8* advance) ok?