Engine Hiccup
10-16-2023, 05:08 PM
#1
6th Gear
Thread Starter
Engine Hiccup
I have an 87' Carrera 120K miles that will sometimes(that's the issue) that will be humming along smoothly and out of nowhere Bam, a hiccup, an intermittent loss of power like no spark/fuel and then a moment later it's OK. Today it just stopped. I pulled over, cranked it over, no start. Waited a few minutes and starts like it was nothing. My question is, do DME relays give a warning like this or should I look at something else. I did make it home and changed out the DME relay and it's running smooth but I am shell shocked to take it out for a test run. Any opinions on this?
10-17-2023, 11:31 AM
#2
Team Owner
My opinion is you have to start somewhere, and on your car that is a great place to start ...
other problem areas
1. Coil make sure it isn't a silver Brazilian one
2. HTS . make sure it is not the 1 wire. if so upgrade it to the 2 wire as the single wires are prone to failure, they cause the car to choke hiccup and die when the engine is warm as it falsely makes the car run too rich.
other problem areas
1. Coil make sure it isn't a silver Brazilian one
2. HTS . make sure it is not the 1 wire. if so upgrade it to the 2 wire as the single wires are prone to failure, they cause the car to choke hiccup and die when the engine is warm as it falsely makes the car run too rich.
10-18-2023, 05:35 AM
#3
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
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These kind of problems can be really painful. My humble suggestion is that there is an occasional electrical break somewhere. I would do following:
- Have the engine idling and touch and wiggle the cables and connectors. Ignition voltage is quite high, I would not touch the ign. cables.
- Disconnect and perhaps use some electrical spray in the crankshaft pos sensor plugs. The 3 connectors on left side engine. They are in a vertical row. Do this to other connectors around engine. Probably not needed for injectors.
- If you have a spare DME relay, swap it. If not, take the cover off and look carefully on the solders. Is there a greyish ring in the otherwise shine solder, if so, resolder.
- Rotate all fuses in their ”sockets” and here perhaps also som electrical spray. There is some fuses also in the engine bay, left side.
- Pull and reconnect carefull the DME plug and check that no oxidation there, check this specially if cabrio or targa.
- When eng dead and you try to start, do the fuel pump run? I don’t believe engine would just suddenly die if fuel pump don’t run.
Do not disconnect anything while engine running or ign on.
I don’t know how the crankshaft pos sensor fail, mine was OK when I parked, next time totally dead.
When my intake manifold gaskets started to leak, cyl #3 got lean and head temp sensor added fuel, engine did run, but poorly.
Keep a list what you have done so you have an idea what you’ve done and can be systematic.
Sorry about my English, I’m not native.
- Have the engine idling and touch and wiggle the cables and connectors. Ignition voltage is quite high, I would not touch the ign. cables.
- Disconnect and perhaps use some electrical spray in the crankshaft pos sensor plugs. The 3 connectors on left side engine. They are in a vertical row. Do this to other connectors around engine. Probably not needed for injectors.
- If you have a spare DME relay, swap it. If not, take the cover off and look carefully on the solders. Is there a greyish ring in the otherwise shine solder, if so, resolder.
- Rotate all fuses in their ”sockets” and here perhaps also som electrical spray. There is some fuses also in the engine bay, left side.
- Pull and reconnect carefull the DME plug and check that no oxidation there, check this specially if cabrio or targa.
- When eng dead and you try to start, do the fuel pump run? I don’t believe engine would just suddenly die if fuel pump don’t run.
Do not disconnect anything while engine running or ign on.
I don’t know how the crankshaft pos sensor fail, mine was OK when I parked, next time totally dead.
When my intake manifold gaskets started to leak, cyl #3 got lean and head temp sensor added fuel, engine did run, but poorly.
Keep a list what you have done so you have an idea what you’ve done and can be systematic.
Sorry about my English, I’m not native.