Surging

Roger Hall · 01-18-2003, 03:33 PM

Well I have finally given up on my 81 924 na. I have replaced

Fuel Injectors
Cold Start Valve
Air Filter
Fuel Filter
Auxilary Air Valve
Rotor
Distributor Cap
Vacum Lines
Negitive Battery Cable
Spark Plugs

I have cleaned all the grounds on the car
I have Checked the throtle position switch's
I have played with the fuel mixture

I have run out of ideas and resources. The car lacks power in first gear. Then when you shift into second after a 3 or 4 seconds the car surges forward and picks up power. Probably at least 15 or 20 horse power. Its like you flipped a switch and the power comes on. There is an intermitened buzzing comming from the fuel distrubutor. I do not remember hearing it befor but it may be normal.

Alot of these things needed to be replaced and it has solved many problems, and some were just regular maintiance. I feel good about the progress I have made with the car, but I am unable to find and fix this problem. It is time to take it to the shop. I wont enjoy spending the money but my own inability to correct the problem really gets to me.

carolinus · 01-19-2003, 07:22 AM

Could you post back here what the outcome of your trip to the mechanic is? Also, have you checked fuel pump output and cyl. compression? Both could screw you up.

I will say I am having almost the same problem. It seems to pick up a whole lot in second gear, though. Anyone got any ideas?

Roger Hall · 01-19-2003, 07:42 AM

Fuel pump output is good about 1800 cc per min. Have not checked compression. I will post back, but it may be a week or so. The shop has a bunch of cars to get ready for Seabring next weekend. I am taking it in on Tuesday but it might be a few days before they get to it.

Roger Hall · 01-19-2003, 07:45 AM

Carolinus just thinking but I doubt its compression. Wouldn't a lack of compression cause an overall lack of power not a surge.

Mike B · 01-19-2003, 08:25 AM

Cars that age sometimes accumulate corrosion in the fuel tank...Of course all the corroded material falls to the bottom of the tank obstructing the flow of fuel...That could explain your surging...Like a blockage being forced open under load...

You might consider draining the tank and removing the pump...I suspect a pile of coarse, sand like corroded tank material will fall out...Best part is you can do this yourself and it will cost nothing...

carolinus · 01-19-2003, 09:46 AM

It could be that we have a problem in all gears, and the gearing in first is exacerbating it. I am going to take my intake system apart and hit what I can with carb cleaner. I am also going to check for vacuum leaks. Gotta get some new intake seals first, though.

I like to run a compression test just on general principles. It can indicate problems elsewhere.

carolinus · 01-19-2003, 09:56 AM

I have a 944, but the two have some similarities. I am going to reflow the joints on the DME relay, in an attempt to stop that problem.

Frank B · 01-19-2003, 10:52 AM

I'd bet my left nut it's a bad head gasket.. have you done a pressure check?.. a bad head gasket will cause serious power loss....or it could be the cam.... but I'd be hard pressed to find anything elase but a bad head or gasket..did you change the fuel pump?....

carolinus · 01-19-2003, 12:50 PM

That is a possibility. I know that I have oil leak out of one of my gaskets (can't tell if it is can housing or head gasket) in the rear passenger side when the car is jacked up in the front and the engine is running at temp. Doesn't do it any other time, though. I will be doing a compression test on Thurs. I don't have any of the other traditional indicators of head gasket failure, though.

Cebu · 01-19-2003, 02:07 PM

Check your voltage regulator output and battery condition, low voltage affect DME operation and spark intensity, this can be noted as an engine power surge.

Frank B · 01-19-2003, 02:22 PM

the first sign is a drop in power...

Roger Hall · 01-19-2003, 06:17 PM

Mine is an 81 924 na I dont think it has a DME.

Mike B
It could be corrision in the fuel tank. I pulled the fuel return line and output was good and clean. Pulling the fuel tank is a great idea since the car sat in a garage for ten years befor I got it.

Frank B
The head gasket could be the problem. I am not excited about replacing it. Nobody has sugested that might be the problem. Can this explain the surge though? The headgasket should cause an overall loss of power. Haynes says retorqueing the head bolts is part of the recomended maintaince, and I couldn't tell you when that was done last. The fuel pump has not been changed. Cam should be good, I can't say for sure but I had the shop replace the timing belt when I first got the car. They changed the valve cover gasket and did not report any problems.

Cebu
I have done quite alot of work to the electrical system. It is operating much better but I have never checked the voltage output. I will try that thanks! Can I mesure the voltage output at the battery or should I do it from the alternator?

carolinus & Frank B
A compression and leak down test are great ideas. I will have to buy a compression gauge this week.

Spark plug wires were repalced befor I got the car. I have been wondering if they might be the problem.

After I replaced the spark plugs I ran the car for 3 miles and when I pulled the #1 plug it looked brand new. Shouldn't it have had some deposits or discoloration?

THANKS FOR THE ADVISE!!!!!! YOU ALL HAVE GIVEN ME SOME NEW IDEAS.

carolinus · 01-20-2003, 06:30 AM

Was it the only one that looked that way, or did all of them? And, have you checked recently? If it were a 944, I might say that a post in your distributor cap has come off for that cyl.

Voltage output problems causing the issue is a very interesting suggestion. I know that my starter really badly sucks (replacing it on thursday), and that I am really drawing a lot of juice to get the car started. I wonder if my trouble could be that I am pulling so many amps that the system is undervolted after I start it until the alternator has a chance to do its thing. Hmm...

BTW, what is the suggested voltage output for the Voltage Regulator? And what is the input voltage range for it to remain functional?

Roger Hall · 01-20-2003, 06:58 AM

I only pulled the #1 plug. It wasn't wet and it didn't smell like gas either. It was strange.

Cebu · 01-20-2003, 01:37 PM

You can check the voltage at the battery. The voltage should 12.5 to 14.5 Volts. The weak battery may also be the cause of your suspect starter problem. Suggest having the charging system checked before investing in a starter. Ensure that the battery cables are not corroded. You may have 12 volts at the battery but low crankiing amps and the starter will drag when attempt to start.

Roger Hall · 01-20-2003, 03:07 PM

I richened up the fuel mixture and the symtoms went away. This makes me think that it has to be a fuel system problem. Since I have no idea if the fuel mixture is off, I am gonna have the shop set it and see if the symptoms go away I am golden. Otherwise its stays in the shop untill its fixed. They couldn't fit me in this week. Alot of them are going to Seabring leaving Wednesday. The car goes in next Monday.

carolinus · 01-20-2003, 05:43 PM

I am going to replace my starter anyway. I had the system load checked, and they said it was fine (2 different places). I finally decided to take the unit out and clean it last month, and found my problem there. The last owner, may he rot in Hell or drive a Ford Escort for the rest of his life (whichever comes first), ran over something HUGE with the car. In the process, he broke the front spoiler, took off several oil cooler fins, and put a huge dent in the starter. One of the through bolts was missing, even. It was sad. I will check my system again, just in case, though.