I recently did a 305TBI to 350 TPi swap in my 92. I assembled the engine myself with some help from KingTal0n. Engine specs are in the sig. I've had the misfortune of having a series of unrelated problems all at once at first start up. Dead battery, coupled with a bad coil, bad ecm (which fried 4 injectors on one bank). Finally have all this straightened out, and by now the engine has roughly 30 minutes of run time.

Throughout the whole process of sorting out these problems, I've had a problem where the engine starts and runs fine for a while, then starts idling rough and dies. Try to start it again, and the starter can't turn the engine over. It doesn't seem to be temperature or run time related. I can keep the engine running at a given rpm as long as I want if I stay on the gas. Once I step off, it idles rough for a second or two, then dies. Does this regardless of the chip tune, and even in limp home mode.

If I let the car sit for an hour, then try to start it, it'll usually fire right up. Its not a charging problem as I originally thought.

The engine starts and runs fine. Starts very easily actually. Feels pretty strong, sounds fine, doesn't smoke. Keep in mind though that this engine is untuned at the moment. Oil pressure gauge is pegged at 60 when I turn the engine on. Check the dipstick, oil level is fine, and I can't find any particles in the oil. Oil looks very very clean. Engine was primed for several minutes before it was run, and it hasn't overheated at any moment.

I was going to try to turn the engine over by hand when its cold, and then after it dies to compare torque readings to see if its locking up, but I don't have a way of turning it other than the crank bolt, and I don't want to do that. I have a crank socket, but I would have to take the balancer off every time I want to check it. I had it off this morning, and the engine would turn several full cycles(two revolutions per cycle) without getting difficult to turn. The engine is a little tight in general, but then again its a fresh engine. Anyone have any ideas of what I can do from here? I'm afraid I screwed something up internally. I really appreciate any help or input on this issue... I'm pretty frustrated and stumped right now.

 

You need to properly tune your car so it will idle w/o dieing. TPS and IAC are a good first place to check, then check your MAF to make sure it's working.


It sounds like you've got a case of the y-pipe rubbing against the starter blues. It sounds like heat soak that makes the car hard to near impossible to start until an hour later. You could try to hook up a remote start to it, if that didnt fix it then you can return it lol.

I really dont think that your engine is siezing up.

 

The bin that it has right now is an AUJP with less fuel and more timing around idle. The engine seems to like it better than the unmodified AJUP, but regardless, it will idle for a while on its own. TPS is set to .45 volts, and minimum air was set. I have a speed density setup, so I don't have a MAF.

The problem is definitely not a hot start issue with the starter and y pipe. I had the same starter and exhaust setup with the 305, and it never did that. Also, you can start the engine completely cold, kill it after 45 seconds of running, and it will not turn over with the starter. Engine has 9.5 to 1 compression, and the starter was taken to get tested and its fine. The engine is still cold after only 45 seconds, so I don't see the starter or solenoid as a problem.

I am getting pretty scared right now, because my dad is telling me that the last two times that I had started it, he heard a very loud clanking sound for about the first half second when the engine fired. It hasn't done that before. Everything seems to be pointing to an internal issue. I really hope its not. I don't have time or money to take this apart again while I'm in school.

 

when you dropped the 350 in, did you put in (or atleast check) the bearings?

Did you replace the oil pump with a new one?

Please elaborate on all that you did in prep work (bottom end related) before you fired it up.

 

The crank was in good shape, so I just installed new set of standard main bearings. I plastigauged it, all the journals were within spec. I also replaced the rod bearings, and installed a new set of cast pistons with rings. I didn't use the stock rods that were in the block, I had the new pistons pressed on a set of X rods that I picked up. As I removed the old main and rod bearings, I examined all of them, and they all looked good. They were all similar in appearance to the others. Once the main caps were installed, I made sure the crank would turn without binding, and it was fine.

The oil pump is not new though, but I don't see how an old pump will cause the engine to seize (provided you have adequate oil pressure of course). Everything was put together with Clevite 77 assembly lube, and every bolt was torqued to spec. I checked every bolt atleast three times with the torque wrench before putting the oil pan on.

I made sure everything was as clean as possible. I used lots of brake clean and cotton rags to clean everything. Not sure what else I can say.... also the engine was primed for several minutes before firing, and there was oil coming out of each pushrod. I really appreciate your help so far, let me know if there is anything else I can mention to help get some ideas as to what I should do next.

 

Anyone have any ideas?

 

How long exactly before it starts to stumble and die. If not long, my initial reaction would be to look for a fuel delivery problem. Have you datalogged it? Watched fuel pressure, voltage, timing?

 

Its not a set amount of run time, and its not temperature related either. Its died before after about a minute of running, or it can do it after several minutes. It lasts longer in general with a completely cold engine. It will run very well for a while, even at idle, and then it will just start vibrating and running rough. After a second or two of this, it dies, and will not turn with the starter. I had initially thought it was a battery charging problem, so I kept the rpms up around 2000 for several minutes, and it stayed running without any problems at all. As soon as I stepped off the gas, it would do the same thing. It behaves the same whether its in closed loop, open loop, regardless of the chip, and even in limp home mode.

I have a Walbro 255, and the afpr is set to 45. The car holds pressure for a long time after priming, and the pressure never drops while the engine is running.

While the car is running, I measured the voltage across the battery terminals, and it is rock steady at 14.3. For reference, my dads 96 G30 van also has the same reading while running, so my alternator seems to be charging fine. Battery holds a charge as well. I stayed on the multimeter measuring the output when the car starts to die, and only while its actually in the process of dying does the voltage drop to around 12ish.

I have been unable to datalog it because I have been unable to connect with my laptop. I have tried Tuner Pro, Craig Moates 852, and DataMaster. None of them have worked. The cable I am using is a two transistor type cable that was working with my old 160 baud setup. I borrowed another laptop, and none of the three programs will connect either. I made a new cable thinking that has to be the problem, but it doesn't work either. I have tried using both pin E and pin M. I have good ground at pin A, and I am getting +5 V on both pins E and M.

Anyways...Timing is set at 10 degrees base, and the base timing has also been set to 10 in the chip. Verified with a timing light that the timing advances with rpm.

 

When you say it will not turn with the starter, do you mean that it won't engage, or it engages and just clicks or it spins the motor and it won't catch or something else? Have you tried pulling the plugs and turning it over manually to dispel the seizing gremlin in your mind?

 

I can feel the starter engage the engine, but while turn the motor over extremely slowly and intermittently or not at all. Doesn't matter if the engine died cold or hot, or how long it was running.

I don't have a way to turn the engine over by hand without pulling the balancer. All I have is a crank socket. I had the balancer off before, and I was able to turn the engine several revolutions with a breaker bar when the engine was cold.

Whats making me think that this is a seizing problem is that the last two times that the engine was started, it made a loud but brief clanking sound as soon as it fired. Sounded similar to a rod knock. The engine will start almost instantly after turning the key, but once it runs for a while, it will die abruptly, and refuse to let the starter turn it.

What I want to do is to measure how much torque is required to turn the engine over cold vs right after it dies. Which reading is supposed to be higher??

 

okay, the balancer pulley's center bolt is a 5/8" socket, turn the motor clockwise (righty tighty) and you can turn it that way... You'll need a deep socket for it, or a 3 inch extension and small socket. This is what I use to turn the engine over... of course, I use a breaker bar (1/2" drive), I dont know if you have a 1/2", or 3/8" drive torque wrench though, you'll probably want to go to sears and get the corresponding socket though

The knocking on start is NOT usual, it didnt happen to our cars brand new, it aint supposed to happen. I'm sorry to tell you this, but when my bearings got shot (you can look at my post here in the tech board with pics of my bearings) it made the same sound on start up, and a slight knock while driving... it would sieze up after i drove it a little bit, just down the street even... though I'm still not 100% confident that wasn't just an idle problem since I've always had a rough idle with the car.

Now why not replace the oil pump while you were in there anyways? Sounds like an idle problem mixed with something like a stuck bendix on your starter...?

 

Before spinning by hand, after that last description, I'd pull the inspection cover and look. I think you may have a starter and flywheel/flexplate problem. I'd look at what happenes when warm and also inspect the flywheel/flexplate for a crack(s).

 

I had pulled the starter off previously to take it to get tested, and it was testing fine. While it was off, I looked at the teeth on the starter, as well as the flywheel, and it doesn't look as if they are misaligned or not engaging properly. When I dropped the engine in, I had inspected the flywheel, pressure plate, and clutch disc before reassembly. They all looked good to me.

I realize that I can try to turn the engine over by using the crank bolt. I have read however, too many horror stories with stripped crank threads, and broken bolts to do this comfortably. I did try to put a socket and breaker bar on the bolt and try to turn the engine, but the bolt would start to turn instead of the engine, so I stopped immediately.

As to not replacing the oil pump while I rebuilt the engine? To be honest, I was not even in a financial situation where I can spend any money on my car, and so my buildup was on a penny pinching budget. I spent about $600 I believe for everything you see in my sig. Some of the parts that aren't really necessary (52 mm tb, aftermarket runners, afpr) I have managed to get free by trading and selling things. Looking back, I shouldn't have overlooked the pump, but I don't have an oil pressure problem right now so thats not on my mind.

I was doing some reasearch on the boards right now, and I came across a post that pointed something out to me that I wasn't aware of before.

I have a set of 416 (305 HO) heads on the engine right now. They came off an 85, just like my manifold. Now, this is a roller block, and I am running a hydraulic roller cam with stamped self aligning rockers. The post I ran into had RB83L69 mentioning that you can't mix self aligning rockers with older heads, or non self aligning with newer heads...or something along those lines....due to different size pushrod slots. I haven't measured or checked clearance here because I wasn't aware of this before. Could this be a problem, or did I misunderstand what RB was trying to point out?

 

You asked earlier about how to turn the motor by hand without taking the balancer off to use a special socket.
I got an old flexplate and elongated 3 of the holes to fit the bolt pattern on the balancer, it works pretty well.

 

I never thought of that before. What do you use to turn the flexplate though? Just your hands? Is there any way to stick a socket or ratchet on it without having to get too creative?

 

Yeah, just rotate the flexplate by hand. But I'll put a rag over it if I'm going to do it a bunch of times cause those gear teeth can bite your hands. The teeth definitely give a good non slip surface though and there's plenty of leverage to turn the motor over if you use both hands.
Also you can put marks on it every 90deg for adjusting lifters.

Another trick that I want to do, but haven't tried yet is to get a scrap crankshaft and cut the front off, then weld a big socket onto the end of it. That could be driven into the gap at the front of the balancer and then turned with a 1/2" drive breaker bar without having to remove the front pulley.

I get nervous about turning the motor over with the balancer bolt, I've seen stripped out bolt holes from that.

 

Thanks for the tip. I'll see if I can find an old flexplate lying around. I have more junk sitting here than I know about.

 

This works really well. No need to touch the centre bolt.

Hope this helps. Good luck with the engine.

Andy.

click here

 

It looks like we have a winner I'm gonna have to get one of those

 

oil pumps are cheap...why not replace it when you are already replacing the bearings????

heres one at autozone...

http://www.autozone.com/servlet/UiBr...7C%7EEA%7C%7EB

did you have the crank checked when you replaced the bearings???...or did you just look for gouges and scratches on it ??

sounds to me like bearings are freezing up on you .....thats my opinion .....

 

By chance, Did you plastigauge the mains and rods? I jsut did my engine and decided to plastigauge them to make sure clearances were in limits. also, did you check the end play of the crankshaft?

having the oil pegged at 60 makes me wonder if the tolerances were too tight? My oil psi is pegged at 60 under wot, but at idle, it's around 45-50. My mains were at .0015, just a thought..?